Definately worth signing up here, I have an account and can vouch that there is tons of information in there. Of course you get a LOT of rubbish aswell but more or less any Internet marketing course you're after will be in there, stockmarket information (tons), there is a lot of poker stuff but personally as a semi pro gambler I would like to see more academic gambling stuff (Leighton Vaughan Williams for instance) in that section.
Somehow I don't have any invites but I have only used the account intermittently of late - so this is a reminder for me to et my account seeding.