There is a good amount of Ubuntu software that is not currently in the Software Center, but that users still want to install. When this happens, we usually tell them to do something like:
tar xf third_part_app.tar.gz
sudo apt-get install dependencies
chmod u+x installer && ./installer
Setting the executable bit and dependency resolution are very roundabout to achieve graphically, so we can either send them to the command line or give them a very lengthy sequence of GUI instructions. And by the way, dependency resolution sometimes requires a lot of back and forth. Which kind of sucks.
Recently several third-party services (eg Desura, Gameolith) have stepped into this niche and offered easy methods of installation for non-USC software. Under what circumstances, if any, is it okay to recommend users install from these services? If these services got into the USC, would they become more recommendable? If they were open source?