The Major Nelson website has the full list of games that will get the extra price reductions this weekend. They include the Halo: The Master Chief Collection Digital bundle (combining the Xbox One game and the live-action movie Halo: Nightfall) for $35.99 for Xbox Live Gold members, and $40.19 for Silver members. If you like fighting games, the Killer Instinct Complete Collection (combining both Killer Instinct Season 1 and 2) can be yours for $47.99 if you are a Gold member, or $53.59 if you are in a Silver member.
If you want to check out Telltale Games' The Walking Dead, you can get the Season 1 and 2 bundle for the Xbox One for $20 if you are a Gold member and $25 with a Silver membership. There's also a sale on the Shadow of Mordor Season Pass, which is priced this weekend at $14.99 for Gold members or $16.74 for silver members.
There are also a bunch of Xbox 360 games that have been added to this sale this weekend; check out the Major Nelson site for all the details.
Source: Major Nelson