Well, I did set up a wiki a while back but forgot to mention it. It has information on every gun and melee weapon (now possibly outdated with all of the buffs and nerfs) as well as every gang and business (also possibly outdated). You can see the wiki
here.
Credits to Rogue for all the slave work (e.g. entering every gun into it).
I'm not going to maintain it but if someone reputable is interested I can set them up as a sysop so they can do whatever they want with it.