At work, we use lots of open source tools

to build things for clients. Our clients

are really more consumers of the services

than the bits generated themselves, if that

makes any sense. (i.e. they don't need

permanent ownership of a given thing, and

don't care what it's written with, so long

as it works for their purposes for the

given interval of time)

Anyway, this has extended to the tools

we use to manage the development process,

namely Bugzilla for QA and cvs for revision

control. We're still working through the

process of integrating everything into the

internal workings of the development flow,

but have so far had very good success with

everything.