My app continues to add about 5,000+ users per day and total user count just passed 650k.<p>7-day rolling-window usage statistics are up about 20% since Nov/Dec and just two days ago hit a new record for number of active users in one day.<p>I don't force users to invite for any features, but every month or two I do flip a switch and have them bounced (just once) to the invite page as a friendly "Hey, tell your friends!" notice. I also run contests that use the invites as entries -- you'd be surprised how many people suddenly love sending invites once they realize more invites = more chances to win a $500 Nintendo Wii gaming package =)<p>Apps are hardly slowing down on Facebook, but I wholeheartedly agree that the problem of forcing invites has become more widespread and needs an immediate fix. That and the ridiculous amount of spammers smearing links all over developer review walls, discussion boards and fb:comment sections.