When my DD#2 turned 3 earlier this year, i hired some 'little tikes' toys......the roller coaster slide (not as scary as it sounds, more for 2-5 yr olds), a basketball hoop and ball and a twirly thing. It cost me about $80 and the kind lady let us loan it for a week, as oppose to just the weekend. Unfortuantly it rained on her birthday - but we just had the toys inside and the kids had great fun.
Libraries also have toys to hire.....or you could google something of the like.

I find with 2 yr olds a lot will just entertain themselves, so dont go too overboard - the pinata for a 2yr old maybe a bit hard to hit - but ive seen these great ones at shops where you just pull a piece of string (there is many strings) and one piece of the many strings is attached to the pinata lolly section......easier for the little ones.

Good luck...