You can install the "Get Bundles" (with an "s" not "Get Bundle"--that's a different Bundle) Bundle
To install:
cd ~/Library/Application\ Support/TextMate/Bundles
svn co http://svn.textmate.org/trunk/Review/Bundles/GetBundles.tmbundle/
(Alternatively, you can grab the "Get Bundles" Bundle from git.)
Once installed, you probably need to re-start TextMate.
Next, click "Bundles" in the Menu Bar, then click "Get Bundles" which will bring up a small sub-menu;
Click "Get Bundles" in that sub-menu.
This will bring up the Get Bundles GUI. In the upper left-hand corner are four buttons that refer to four different repositories ("Official", "Review", "3rd Party", and "All").
Click the right-most button "All"
In the bottom left-hand cornder of the GUI, click the "gear menu" which will bring up a menu, click "Install all Updates" from that menu (also accessible with cmd-U).