1. Put the music on an external disk. But then I'll want copies of some of the music on the laptop so I have music away from my desk. Which means I need to figure out the best way to manage the "full library" and the "portable library". Unless there's a good app for dealing with this, I expect it would involve having a separate account that points to the music on the Drobo, then logging into that when I want to sync the iPod.
2. Buying a larger HDD for the MacBook Pro. So far that's sounding easier. Just costlier. Perhaps I shall put off the whole exercise till I have no choice but to upgrade do to other stuff.
Any ideas on software to manage #1, or other suggestions on what to do when your music doesn't fit on your computer?
EDIT: Is there anything Google can't answer? A forum post notes that iTunes supports multiple libraries (just hold down Option when launching iTunes), so there's no need for a different account.
EDIT #2: And another Google search will help me move the iTunes library and not just the music. (The forum post, admittedly from 2007, talks about deleting the library – no way!)