I'm the guy my friends ask favors of because I almost never say no.
As an INTP, I guess I'm more of a thinker more than a doer. My job affords me the opportunity to be a little experimental and involves a lot of thought as well as occasional flare-ups of total insanity, so it suits me well. I can toil away in the lab and be the hero when something breaks.
I can be a bit of an idealist. Thinking things are more like I wish they were than they actually are. Thinking people are more often than not generally driven by the want to do something good. I'm not going to look at a person and make snap judgements about who they are. I've met too many awesome people that would have been shunned by a closed mind.