Mining for bitcoins on GPUs is fun, especially if you have 3 video cards in one system. This income can, however, be supplemented by some foraging for free micro-bitcoins. This does not bring much to your wallet, but the total amount can be acceptable if the foraging does not require much of your time.

Below is a selection of sites, which I found to be more productive and less demanding on your attention. This list is compiled from a much wider selection, presented in this thread on Bitcointalk.

1. BitVisitor – Visit a random site after captcha to get a delayed payout. Many sites can be visited with 5 minute intervals.
2. CoinTube – Earn 10 uBTC for Every Video Watched.
3. Free bitcoins.me – Every 30 minutes, delayed payout
4. El Bitcoin Gratis – Every 30 minutes, delayed payout
5. BTC4You – Every 30 minutes, delayed payout
6. FaucetBTC – Every 30 minutes, delayed payout
7. Can Has Bitcoin – Every 30 minutes, delayed payout
8. Daily Bitcoin – Hourly, accumulated payout-on-demand
9. CoinAd – Visit ad sites. Delayed payout.
10. Bitcoins 4 Me! – Hourly, delayed payout
11. BitHits.info – 3 hits per IP per day per address, delayed payout
12. CoinReaper – Daily, has its own bonus payout, aggregator over several other sites
13. Bitcoin Tree – Daily, accumulated payout-on-demand
14. Bitcoiner.net – Daily, payout-on-demand
15. Bunny Run – Daily, delayed payout
16. Netlookup.se – Daily, delayed payout
17. cointicket.org – Daily, delayed payout

If you find this collection useful, a small portion of your foraging is welcome as a donation to 1DodoExzsNPvVRXFrgkKw6E259VjfUW8Kh as a contribution to my Durrell Wildlife Conservation Trust bitcoin fund-raising drive.