I originally started with a version of Bort that I forked and added a few of my own things to. Now I like to start with BaseApp. BaseApp gives you a more polished feel out of the box and navigation system, admin control panel, etc. Really depends on how much out-of-box stuff you are willing to accept (or modify later) vs. build yourself. I imagine it varies between projects, but BaseApp is always a good start.
As someone said, BaseAPP is a good start.
You could also customize and make your own version, for example, I wanted to have a base in portuguese, with pages, news. etc, so I ended up making my own version: http://github.com/psousa/baseapp-orange/tree/master
imagination is the key. :)
Boiler is a base Rails 2.2 application originally copied from Bort. Bort is developed and maintained by Fudge Studios, Jim Neath and Matt Hall. Boiler is currently developed and maintained by Vertis. http://github.com/vertis/boiler/tree/master
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