http://majornelson.com/archive/2010/06/22/sonic-is-19-years-old-let-s-celebrate-with-some-deals.aspx     
 
If you thought $5 was too much for any of the first four Sonic platformers for Genesis or just never got around to buying them, this Thursday Sonic is getting wasted on some Labatts and Molsons and will be (personally) cutting $2 off the price of each of his 2D Genesis platformers.  
 
For whatever reason, I've yet to buy (on XBLA) any games of the franchise that practically defined my childhood gaming experience.  I plan to grab the only good Sonic games this Thursday, though.  Maybe I'll get Sonic 3 and Sonic and Knuckles, too. 
 
Okay, fine, I'm being a little harsh: Sonic Spinball is kind of fun too, but it's not on XBLA.