The one we we've been handing out says "FREE DMITRY!" (black text on white background) and includes the URL http://www.FreeSklyarov.org on the bottom so people have a clue where to go find out who Dmitry is and why they should care.
The text is a StarOffice 5 or RTF document, if you want to make changes.
I printed the PostScript file on full-page label stock and then covered the page with a laminating sheet (both of which can be found at most major office supply stores--I used Avery 8165 labels and Avery self-adhesive laminating sheets). Just print, laminate, trim (there are three per page), and distribute.
These labels come in packs of 25, but I could only find the laminating sheets in boxes of 50. Materials for a set of 75 finished stickers cost me about $20. With lamination, that's about 27 cents per sticker; if you don't bother with laminating, the labels themselves are only about $10 (13 cents per sticker).