Know of Substantial Apps Written in Python?

[Dry Ice]

Know of substantial apps written in Python?

Preferably something one could download for
examination.

Source code would be nice, but not essential.

I'm operating under the theory that whatever
the POTENTIAL of a language, or the 'elegance'
of a language's syntax and structure, how large
apps actually behave in the real world will speak
volumes.

I like, for example, much about Java.  But nearly
every example I have seen running in the Windows
environment has been slow, leaked resources and
eventually contributed to system crashes.

(I don't care whether it's the language or the OS
or the VM or even "bad programming."  What counts
are the usual results obtained by normal application
developers.)

Suggestions?