There is no limit since the recipient doesn't pay taxes on gifts, the donor does.

A donor can contribute $13K per person without incurring taxes. There is also a lifetime exclusion that may be applied.

As much as you want; You, as a recipient, can receive any amount of cash as gifts without paying taxes if it is truly gifts for you. Donator needs to pay tax if he/she gives you more than $13,000 per year in 2010(I guess)
. For a reference, in the US, a donor generally pays the gift tax. Under certain arrangements,i.e. a net gift, the donee may pay the tax instead.