[Silenced Soul]

You can do this really simply, just make a new profile field with this set up:
Field Required? No
Field Hidden? No
Field Editable by user? No

Submit it.

Then, after you've saved it, click on that codes edit link, and look at the profile field number, it'll be something like profilefield=6.

Then, in the postbit template, where you want the pic or text to show up, put $post[field#].

This is the easiest way to do it, the only thing is, you'll have to edit the users individually....otherwise, you could make it editable by users, and tell in the description they have three options. Your site, other site, or blank.