One of the more popular online-only poker variants has been 888poker's long-running "Push or Fold" format.
The no-limit hold'em variant invites players to join a six-handed table where the maximum buy-in is only five big blinds (as opposed to the usual 100 BB max.). The result is a fast-paced game which satisfies recreational players' desire for quick, entertaining sessions full of action. The "Push or Fold" tables have also proven useful to more serious players looking to sharpen their short-stacked strategy.
However, while players can't buy in for more than five big blinds, those who win do stick around, which can create an interesting dynamic at the "Push or Fold" tables.