I also use a lot of different machines, but I keep all my vimfiles, including plugins, in a repository. This keeps it fairly simple to add plugins to all computers.
This is my configuration: http://bitbucket.org/johannes/vimfiles/src
This is my configuration: http://bitbucket.org/johannes/vimfiles/src
I'm a netadmin doing a sysadmin's job, though. If I was slingin' code regularly, I'd use several plugins.
When I wear my developer hat, I dig nerdtree and vimoutliner.