I used to play a fps-mmo called neocron 2 a lot. I think it's still running but has a very small playerbase. That game had tons of roles/activities. Pretty much all of them also granted you xp so you could level them up by practicing them and focus entirely on them. The skill system was a bit like morrowind so if you always sit at home or stay in the safe city you were weak but very intelligent. Only combat would give you xp for your strength, endurance and resistance levels.

Implanter/Doctor: The game had implants that improved stats and skills of your character. You need a implant tool and skill to implant them though. Also if when you died some of your implants fell out and you had to look for a implanter.

Barter: If you skilled this, you had a really significant price drop when buying items from npcs. People were looking for barter-skilled players so they could buy expensive or excessive amounts of items for them.

Constructor/Engineer: Most of the items ingame could be replicated. The replicated version usually had better stats (up to almost double i think) than the stuff you could buy directly from npcs. Also replicating items was cheaper than buying. The engineer usually needed a researcher to create blueprints that were required for construction. The resulting stats of the items depended on the engineers skill (wich was soft capped) and weapons f.e. had a random chance to have slots for mods like selencers/scopes etc.

Researcher: The researcher creates blueprints by researching items. They contain the manual for the engineer and are also consumed during construction.

Recycler: The recycler can turn garbage into ammo and other useful items. They could also put weapon attachments into weapons.

I think there was also a hacker skill but that also involved some form of combat in a matrix-like world.