For RTS fans, Supreme Commander and Forged Alliance are on sale for $3.74 each (or you can get both for $4.99 in the Gold edition) on Steam.
Supreme Commander
http://store.steampowered.com/app/93...r=1_4_4__106_1
Supreme Commander: Forged Alliance
store.steampowered.com/app/9420/?snr=1_4_4__106_1
Supreme Commander Gold
http://store.steampowered.com/sub/11732/