All of the weapons, both shareware and registered.

Shareware weapons:

WeaponAmmo
Kick- Use this if you don't want an audible sound. Or if you're out of ammo, but I don't see how you could do that. If you've got another weapon selected, you can press the tilde (~) key. None/unlimited
This is the good 'ol pistol. In an unmodified .con, it's weak, but accurate. 12 shots per clip, 12 shots per ammo pack. Max of 200 shots.
The shotgun is significantly more powerful than the pistol, but it has to reload after every shot. Fortunately, the shotgun's reload is faster than the pistol's. Ammo packs contain 10 shots. The shotgun has an ammo limit of 50. If you get a shotgun from a pig cop, the ammo you get is random.
The Chaingun is a VERY rapid fire gun. It is a very powerful weapon, and is especially useful when dispersing lots of baddies. Ammo packs contain 50 shots. The ripper has an ammo limit of 200. Unfortunately, the ripper uses up ammo very quickly, and if you use it a lot, you will often find yourself low on ammo.
The RPG is one of my favorite weapons. It is powerful, and the grenade travels far and even homes in on nearby enemies. The downside is that you can get blasted too in small rooms or tight spaces. Ammo packs contain 5 shots. The RPG has an ammo limit of 50. The slowest firing weapon besides the tripbomb (or maybe the Shotgun), the RPG uses ammo slowly. Fortunately, one or two shots is enough to take out a non-boss.
The Pipebomb is best used for setting traps or getting enemies without being able to be fired on. You can detonate a pipebomb from anywhere, even when looking at a monitor. :-) Ammo packs contain 5 bombs. You can carry a max of 50 pipebombs. An interesting property of pipebomb ammo: pick up some ammo, and you get the weapon! With all other weapons, you can't use the ammo until you get the weapon.

Registered only weapons:

WeaponAmmo
The shrinker is a very cool weapon. Blast a baddie, and he shrinks down to mere inches! Foot fodder! WARNING: Be careful around mirrors! Ammo packs contain 5 shots. The Shrinker has an ammo limit of 50. The shrinker is another slow-firing weapon. It is not very useful against many enemies, and is hard to use.
The Microvave gun (PPak only) heats enemies up until they explode! What fun! You better stand back, though, because the explosion can hurt you (or other enemies). Ammo packs contain 20 shots, a fair amount. It has an ammo limit of 50, though. It uses ammo surprisingly quickly, so be careful not to waste ammo.
The Devastator is my favorite weapon. It launches mini-missiles towards your target, and can blast anything to pieces! It is rapid-fire, and can destroy the final boss in seconds (with a hacked .con file)! Ammo packs contain 15 shots, quite a bit. The devastator has an ammo limit of 99.
The Tripbomb is a wall-mounted explosive device with a laser tripwire to set it off. It is best used in DukeMatch for setting traps, but you can booby-trap a Holoduke (the bait) with one. Found in single units only. You can carry a max of 10.
The freezer is probably the fastest firing weapon of all. It freezes a baddie in his tracks so you can shatter him with a kick. I don't use the freezer much, but freezing and re-freezing a pigcop is a great way to get lots Ammo packs contain 25 shots! The freezer has an ammo limit of 99. The freezer uses ammo quickly, so beware!