coan.net: The typical way of avoiding people "sitting out" when it's their turn to be a blind is to require people to pay a big (or small) blind when joining a game in progress. Either by having them wait until they the big blind rotate to their seat, or by having them pay a big blind for the first hand they play after joining.

Alternatively, one could get rid of the blinds all together and require everyone to play an ante. But it's common for Texas Hold Em to have blinds instead of antes.