Convenient way to set "root of my project"?

[Brett Hoerner <bretthoerner@gmail.com>]

I'd like for commands like "grep" and "find file" to open at the root
of my "project" (I know emacs has no knowledge of projects).  Does
anyone do / use something similar?

For example, I'm in /foo/bar/blah/doo/woo/file and I M-x grep, it's
based in /foo/bar/blah/doo/woo/ and I don't want to take the time to
change the path every time - 99% of the time I want to search my
current project (let's say /foo) for something.  Ditto for find-file,
changes are the file I want isn't in /foo/bar/blah/doo/woo/, but
somewhere further up the tree (and down another branch), I'd love to
start at /foo.

Ideas?  Or maybe I'm using both of these wrong and someone can tell me
the proper emacs-foo?

Thanks,
Brett