WRAPmail - earn advertising commission, anyone heard on them?

I came across this site wrapmail (cant post url's but do a google search - its the first listing) after reading a Zac Johnson blog post... Its an email letterhead type thing with advertising/PPC within the email. Just wondering if anyone has used this and whether or not it is worth signing up for? I guess $50 isn't much if you can get commissions through advertising in blank space in your emails to friends, colleagues etc, but just wanted some feedback first.

I have never tried this, but looks like this thing works.