<p>Does anyone here have any useful code which uses reduce() function in python? Is there any code other than the usual + and * that we see in the examples?</p>

<p>Refer <a href="http://www.artima.com/weblogs/viewpost.jsp?thread=98196" rel="noreferrer">Fate of reduce() in Python 3000</a> by GvR</p>

Not sure if this is what you are after but you can
search source code on Google
.
Follow the link for a search on
'function:reduce() lang:python'
on Google Code search
At first glance the following projects use
```
reduce()
```
MoinMoin
Zope
Numeric
ScientificPython
etc. etc. but then these are hardly surprising since they are huge projects.
The functionality of reduce can be done using function recursion which I guess Guido thought was more explicit.
Update:
Since Google's Code Search was discontinued on 15-Jan-2012, besides reverting to regular Google searches, there's something called
Code Snippets Collection
that looks promising. A number of other resources are mentioned in answers this (closed) question
Replacement for Google Code Search?
.
Update 2 (29-May-2017):
A good source for Python examples (in open-source code) is the
Nullege search engine
.