First, Ryan at The Great Orioles Autograph Project is running a contest where you fill out an MLB postseason bracket. Promote it on your blog and you can fill out an extra entry.
I think every blog in my list has already promoted this one, but The Card Hobbyist is having his first contest as well, which is going to last through all of October. Get over there now for an early entry and promote it for two more.
Also, SpastikMooss at The Great Sports Name Hall of Fame is selling off some hits and trade bait to fund his purchase of a Seneca Wallace 1/1. It's not a contest, but he's got some cool stuff, so go help him out if anything looks good.