The first Saturday in May is Free Comic Book Day, as everyone who is a giant dork like me knows. You can use this handy Store Locator to find a participating shop near you.
If you live in Houston, I recommend the Bedrock City chain of stores. Especially since they almost always have special events for FCBD (even if they aren't listed on the FCBD site).
Today is also the first Independent Bookstore Day, expanding from the previous California Bookstore Days. (I think it was bad planning to have both of these things on the same day, because now I have a ton of bookstores to hit!)
You can locate a participating store near you here. In Houston, Brazos Bookstore, Blue Willow Bookshop, and Katy Budget Books are all participating. I've never been to Brazos, but KBB is the bookstore of my childhood and Blue Willow is a fantastic little place. So check 'em out!