If you go to the market and search for "barcode scanner" you'll get a lot of choices. Most of the scanners will now scan both the standard barcodes and the QR codes. Some will also generate QR codes for you. Here a 3 I've used and like.
RedLaser, I started using it a long time ago with my iPhone and still like it. https://market.android.com/details?id=com.ebay.redlaser&feature=search_result#?t=W251bGwsMSwxLDEsImNvbS5lYmF5LnJlZGxhc2VyIl0.http://
Plenty of others. Just look at the ones that have the best ratings, try some and decide on one you like best. You can always just delete the ones you don't like.
I use ScanLife by Scanbuy myself (I have it for my iPhone now but I originally had it on my HTC Eris, worked fine on both)