I've set myself the goal of doing 50 parkruns by the end of 2013, with the intention of getting to 25 by the end of 2012. I'd also eventually like to do 20 different ones, with the aim of getting to 10 by the time I've got my 50 t-shirt.
I ran my 25th parkrun on the 29th December and my 26th on New Year's Day. I've managed 7 different parkruns so far.