Xbox live sales

I've heard there are sales for xbox live arcade games and games on demand, similar to steam sales. How do I figure out when these are happening? I don't see like a store hub or anything with announcements.

Aren't they usually on the tail end of spotlight channel?
 
Also I think you have to be a Gold member, I don't remember exactly I haven't used my 360 in awhile.

In terms of specific sales, I don't think there is anything for it. There is though a best selling section in the Live dashboard and Major Nelson's weekly report.

There's a panel under Spotlight that'll say "Deal of the Week" You can check see the weekly special there, or go under recently reduced to see permanent price drops.

XBLA sales aren't as big (and frequent) as Steam sales. Like ThePhantomnaut stated, they are posted in the dashboard.

I usually just check here. He keeps it updated pretty nicely.

http://www.cheapassgamer.com/forums/showthread.php?t=283304

this is usually when we get more frequent XBLA sales. Can't wait for the end of the year sale.

They have had some really good sales there. I believe it is pretty much always 50% off.