GMail invitations
Clever buggers those fellas over Google. Once you become a GMail beta tester, they give you 3 invitations per month to send out to friends.
As I've been a beta tester for 2 months, I have 6 invites.
Local Stone readers who want an invitation to get your own personal GMail account, with 1 GB of data storage, write in! (but as I am at work, hit me at news @ salesladder DOT com, OK?)
Note: these are going for as much as $25 each on eBay right now.
