There are several that have a lot combined together. I believe the largest other than the community sources that installs by default with Installer is http://ride4.org/shai.xml
One thing that you should keep in mind, once a day when you start installer it will have to refresh the sources. This can take a long long time if you have a lot of sources. Mine takes close to 5 minutes to refresh. I suggest instead of just adding every source you can find is to go to http://iappcat.com/ and browse through the different sources and software available. Then just add those sources that sound interesting to you. Many of the large source repo's have foreign langauge software, patches for earlier versions of the firmware, etc.. that you wont need or want and just adds to the refresh time as well as having an enormous list of software to scroll through on the phone.