Here is some great add-ons that you mite find useful.
1, Chatroom) 99chats.com lets you create a 100% free chatroom in any size you like, plus also create your own theme with out any ads.
2, Video Room) dialogoo.com lets you add a video/audio free chat room with others.
3, Forums/surveys) wufoo.com lets you create up to 3 forums/surveys for free.
4, Games Center) gametreat.com lets you add a games center onto your site free.
5, ShareThis) sharethis.com lets you create a share widget to share contents free to facebook & etc.
I rely hope these are useful to everyone, i find these great on my site.