perhaps a commenting system like say in vBulletin..
u can add friends and stuff not social group stuff tho..
great homepage with turnable on and off right and left column and middle part should be where all pages change.. [it would be nice if source is fast and less query consuming]
easy to understand coding and every aspect of a normal torrent site [donation page etc]
perhaps some ideas from here -
viewtopic.php?f=29&t=555&st=0&sk=t&sd=a