Appvent are offering a link to one free iDevice game everyday till Christmas, including a "suprise" on 23rd and 24th.
They are making paid games free for 24 hours, 1 on each day, so this is different from the many other free games available on the App Store.
Quoting from their site:
"Every day from december 1th until december 22th there will be one iPhone game free for 24 hours worldwide.
December 23th and 24th there will be no free games but you will find other great surprises here."
Hope this comes in useful to people buying new iPhones/iPod touches in the xmas period.