Hi- check out my site: http://www.bannerworldtrade.com its a great free link exchange that is growing in size all the time. No restrictions on pr etc- some of the sites on the exchange are pr4+ though!

You just register, upload your links, and put the code on your site.

There are various categories to ensure that your link is targeted, if you don't see a suitable category there let me know and I'll add it!

Regards
Chris