Sounds awesome dude. That D&D wiki has alot of useful tips on homebrew diseases.

If you play on the net or have YIM, I'd love to be some cultist or any warlock type disease spreader npc. If you ask me, there ain't enough posions/diseases in D&D!

http://en.wikipedia.org/wiki/List_of...tious_diseases

Real diseases could give you some ideas based on their effects.

I think if I ever get into a game irl I'll try and work on invocations for a warlock like lesser inflict disease/poison, greater, etc. And use a feat to add them to my invocation blast. But I'm glad to see someone else appreciating bio-hazards.