There's plenty for everybody on the PlayStation Store today. I hope. Otherwise I'll look stupid for saying that.
There are demos of Castlevania: Lords of Shadow (review), MMA, My Sims: Sky Heroes (aerial combat) and WRC FIA World Rally Championship.
There are also free trials of this week's new games: the excellent Lara Croft and the Guardian of Light, DeathSpank: Thongs of Virtue and TerRover.