Here are tons of recipes:
And if you're okay when the chemicals, lots of new primers and pore minimizing foundations out there. Partly depends on whether you break out easily or not re: how well some of these things will work for you.
In the past I've over-washed my face when it's hot. This is a better option: http://www.ehow.com/how_8188863_make...-spritzer.html to mist on, if that's an issue.
Oooh thanks Melinda and Rachel for these ideas! My pores are getting bigger now too :/