When I was in elementary school, we typically started out math with a "mad minute": a sheet of simple addition (or subtraction, or multiplication) problems, attempting to finish as many as we could in one minute.
I've been trying to replicate this for my son, and though I've found some mad minutes on the web, I've found it much easier with the large wipe-off placemats--addition and multiplication--at Mardel right now for $.99, available in their educational bargains section (they also have handwriting practice). It's a daily workbox at our house.
For my first grader, I give him two minutes rather than one to complete as many as he can of the 50 problems; he doesn't have to do them in order. (That's for the addition facts of 1-5; he gets three minutes for the facts of 5-10). Once I found what his average and his "best" were, I give him small rewards for completing 25 problems or more accurately, for example. Often, my little competitor wants to try again to best his record!
The wipe-off placemat makes it a little more convenient, not to mention green--and more fun for him. And his fluency in basic problems is certainly improving!