My experience includes everything from designing the tools required to get a specific job done to several stints as a contractor for various clients.
I'm put in my time in Helpdesk and NOC roles, and help design/administer active directory networks at the core of a Federal Government client's backbone to making their backup and anti-virus implementations actually work as they were expected to.
Some of my contracts have included work for the US Federal Government and work at Microsoft Corp (as the friendly voice on the phone explaining how to fix the issue at hand).
I write software, build databases, perform support support for a wide range of operating systems (Win9x,2k,xp,2k3,Vista, Win2008, Mac OS X, Sun, linux (SuSE and gentoo) and somehow find time to unplug and spend time away from computers.
If you really want to get to know your linux distribution from the ground up, check out Gentoo.
Gentoo is all about customization, so have at it.