I found this very useful, and is always nice to have. Xm360 will unlock DLC or XBLA you add to your HDD. It can also be setup to exclude previously unlocked DLC and XBLA and track XBLA you have and see what you have left to collect.

Xm360v1.2 Download

Steps:

1) Unzip xm360v1.2

2) Drag entire folder onto your HDD you use for your JTAG (I use an external 250GB)

3) Run XM360.xex Through XeXMenu, FSD, etc.

4) It will scan your HDD for any content you have added and you will notice little locks (it will either be locked or unlocked)

5) Navigate to either content you would like to unlock and choose the unlock option, then you have it ready for use! (For DLC make sure you have the right TU's in your cache to use them before you start complaining!)