Spears
Man, ain't no-one gonna endure getting the pointy end of a stick jabbed at them without some decent reflexes!
Spears skill determines your effectiveness while using polearms. Spears are generally much heavier than standard weapons, and are usually quite slow, but have high damage output to offput it. Spears most commonly do stabbing damage, though some do Slash as well.
Advantages
High-end spears such as the Chainsaw lance, Garden Weasel or Zap Brannigan tend to be very damaging and scale very well with brawn and endurance. They also can accept a wide range of mods compared to other weapons. Every spear is also at least PC1, and still more are PC2, allowing you to parry fists and whips with ease. The high endurance also helps greatly with drugs, so most spearmen are expected to get high as a kite on coke and speed. Spears also have a +5 bonus to parrying on all two-handed spears, and a 2.5 bonus on all one-handed spears.
Disadvantages
Spears are very heavy, compared to other weapons. They're also generally very slow and take a lot of reflexes to reach usual speed, and are still beaten out easily by Whips and Fists. Unless you take Chromemouth and minmax your to-hit, then you'll be at a much lower to-hit compared to other weapons by endgame.
Weapons
Here's a quick overview of some of the more notable spears in the game. A more exhaustive list can be found on the Weaponry page.
Military Fork - The first spear for newbies who pick the spears class without any XP under their belts. Nothing amazing, but it'll punch through chuds just fine until you get the cash and experience to get an upgrade.
Infected Syringe - Infects anyone who it hits without Hyperimmune with Ebola and causes large amounts of bleeding. Sometimes used by serial killers and drops off of Doctor Shunt. This isn't a one-shot machine, however; Ebola is only truly dangerous to newer players, who haven't maxed out their HP pools yet and don't have the medic skill to cure the ailment.
Assegai - This thing's a footnote. Used in crafting the Large Scythe, but otherwise inferior to the Abossegai in every way. Most people only get their hands on one when they kill a certain Nazi scumbag on Stormfront Island.
Luftspeer - Premodded with balanced grip, monowire and sharpening kit. Has some extra electric damage. One time reward from a journal.
Large Scythe - Crafted. Fairly slow speed, even by spears standards, but hits with solid slash damage if you've got the brawn and monowire to support it (caps out at around 50 slash). Outclassed by the chainsaw lance at the top end, but much easier to max out than the lance.
Pitchfork - Dropped by farmers in Macero, as well as the odd freak in the Toxic Dump. Good crit rate.
Corrosive Pike - Does rare acid damage that can scale high with enough brawn, and gets respectable to-hit. Followed by an undeserved reputation of being "average", this thing is a diamond in the rough. Can only accept two modifications; one of these should absolutely be the monowire serrator, to max out the weapon's acid damage potential. Not much good in PvE, because few mobs are weak to acid that aren't weak to everything else anyway and the pike's a one-trick pony outside of it's special typing.
Abossegai - Other weapons wish they were an Abossegai; this thing's a monster. High minimum damage, and the max can push towards 50 stab (scaling with brawn). Also one-handed, leaving your other hand free for either grabbing/nanite spam/other mischief or horrendously powerful dual-wielding. To top it all off, relatively easily acquired in the Necropolis.
Willy Pete - A disappointing weapon. In theory, this thing would be great for Nullianac packs, punching through their poor burn soaks. In practise, it's slow and inaccurate and simply outclassed by the Abossegai.
Garden Weasel - The straight-laced fighter's spear. No tricks or special damage types, but gets good to-hit, good damage and good speed without much difficulty, and is very lightweight. Decent skill scaling, but brawn brings out its true potential. Found either from toxic freaks or from the chud-only shop.
Chainsaw Lance - A rather obnoxious weapon that will only tolerate strictly excellent stats in its wielder, or else it will sulkily put out only mediocre performance. Difficult to speedcap at 31 reflexes, but caps at a blazing (by spears standards) 2.6 speed. Also requires top-notch brawn to exploit its high damage output, but can push towards 55 slash damage per hit when properly babysat on top of 4-8 bleed damage and an excellent crit rate. Also suffers from an innate to-hit penalty and cannot accept any grip mod aside from the grip tape mods. Monowire for this is a must to max out its damage.
Titanium Bo Staff - Crafted, with the schematic being rather difficult to acquire and the recipe itself quite tedious. However, the staff is very fast, has solid to-hit, and puts out beat damage (one of the scarier damage types) like no tomorrow.
Zap Brannigan - The former best spear in the game. Fairly difficult to craft, but gets good to-hit and does a healthy amount of stab and electric damage. Quite nasty in PvP, where few people soak electric damage.
Mods
Elemental - Either butane or shock mods. Only put EMP on specialized weapons to use for ghostbusting. Acid pump kits should be considered for corrosive pikes.
Grip - In PvE, always use balanced grip, to counteract slow speed on the majority of spears. In PvP, drugs should be used to counter-act the slow speed, and you should use a gyro grip instead.
Monowire Serrator - Best used on the Chainsaw Lance, although it works just as well on everything else for brawn builds.
Sharpening kit - Use on pretty much every spear.
Racials
What to consider when picking your racial mutation:
Abomination - A popular combination back when abomination itself was popular. Hideous Freak and abomination both buff endurance and the latter in particular also boosts brawn. The synergy with abomination and drugs also helps tons since spears rely on drugs to overpower their opponents.
Hideous Freak - Should you choose to forego brawn and pick senses instead as your third stat, Hideous Freak by itself should prove to be a worthwhile racial, taking your focus to the levels of endurance whips, at more than 40 without buffs.
Vampire - The buff to brawn takes the brawn-scaling spears to a whole new level, but since vampire is incompatible with the two most popular endurance buffing mutations, there's a net zero gain in endurance. Also, being a vampire sucks.
Zombie - Buffs endurance and brawn, helping you take advantage of brawn-scaling weapons easier while also giving you more of the much-needed to-hit. Zombie also gives some resistance to drug addiction, an invaluable addition to a spearman's arsenal. Zombie's natural slowness means that the slow speed of some spears such as the large scythe or the chainsaw lance, aren't as crippling. On top of all that, the spears' tendency towards tanking out your opponents because of their high parry bonus go hand in hand with zombie's natural tankiness (the soaks and the damage reduction).
Chud - You can access garden weasels much easier than most by simply buying them from the chud-only shop, rather than waiting for another chud to buy it for you or finding it in the toxic dump.
Chromemouth - Chromemouth buffs endurance by 3, a significant buff without many downsides, making it the natural choice if you've been turned off by every other racial. You'll have a sizeable to-hit and some minor bonuses to useful skills. However, you won't really be able to take advantage of Chromemouth's main draw, Zero, because you won't have the cool to pull it off.
Strategy
PVE Bo Staff, Garden Weasel or dual-wielded abossegais can very easily cut down most mobs, use power attacks liberally.
PVP PC2 on the vast majority of spears is a definite bonus in PvP, and the chainsaw lance can cut through most soaks by value of bleed damage. However, its low accuracy can be a turn-off if you're fighting particularly dodgy players. Dual abossegais are brutally strong if you are the brawny type. Garden weasels, bo staves and zap brannigans are accurate, fast and deadly, the top choice in most situations.