My mom is a freelance writer. Only contact she makes with people is via the internet. It takes a while to actually make money off it, though. The company she works for, you have to reach a really high level to make an average sized paycheck. She enjoys it, however.

I would think many computer jobs would have limited interaction. However, you still might have to interact with at least one other person. If you're good with computers and/or writing, though, it's something to consider.

If it's easier for you to be around children than adults, a teacher might work out.

If it's easier for you to be around pets than people, then a job working with animals might be an idea (yeah, you have to deal with people, too - but I find it easier to deal with people when animals are in the picture).

Red Panda is right. It comes down to what you want more than anything. There are options, but you should always keep in mind that you will have some form of interaction. Even in my mom's case, although it's all online.