i have the concrete monster problem at my house, heres what you do:
1. think about which way the piece bounced
2. DO NOT sweep the floor
3. Blow on the floor gently so your eye will catch anything that moves
4. If that fails, consider looking in another possible area
5. consider the size of the part, the smaller, the more it could have bounced and the harder it will be to find
6. If all else fail, bring out the shop vac, and search through the drum when your done