Hypothetically, if someone had access to another's pertinent personal info (and knew them personally), what sort of havok could be wreaked on their life soley via the internet? I want to hear some creative ideas!

Lol, introduce them to totse.

I was also thinking of that lol.
You can post their personal info, e-mail etc. to a pedo or gay forums... send gore and guru images with foul language to all his/her friends in facebook, myspace...

/b/ is your personal army. They may say otherwise, but post an email saying that it will eventually lead to bewbs, and the recipient is done for.

Just don't post it here, because we don't allow that particular brand of shit.

Good ideas, but I'm thinking more along the lines of information like SS #s, date of birth, etc... Not so far as financial information per-se, but more like what one might find on a job app or school record. I'm talking about going a little beyond posting mean things on their Myspaces. ;)

Then again, like you guys said, I guess 4chan... :P

Credit card fraud under their name would be a good one surely?

Set up sex addict/AA/nazi meetings at their house. Obviously via the respective forums.

thinking of more.. will get back to you

You answered your own question. Fake job application forms, find out what places he's applying to, or send out opportunities to work from home under a fake company, have them fill in the form.

Or just keylog them.