Yes, you can and should be picky if you want your site to have any PR whatsoever.
I typically do not link to ezboards, but I know there are some good ones out there.
Also, the ones that are contacting you… be very wary. Many of them are black hat sites. Check their linking scheme…. lots of them are like this:
link to my site http://www.mysite.com
your link will be placed on http://www.mysite.abcinfo.com
Those suck and are all over the place.. same with:
http://www.mysite.verynice.com
Be veeeeeery careful.