When I travel, I don't pack up the desktop I use in the office and take it with me. Maybe I should, but I don't. However, since I'm a contract programmer I like to be able to work wherever I am:

I'm mostly thinking of web development here. Version Control goes a long way in keeping sane and working on multiple projects on multiple systems (two or three computers); however, there are the issues of:

• IDE settings - different display sizes mean the IDE settings can't be completely synced, if at all.
• Database - if the database is 'external' (even if it's running on the same system, it's not in version control), how do you maintain the needed syncs of structure.
• Development Stack - Some projects need non-standard extensions, libraries, etc installed.

Just an overview of some of the hassle involved with developing on multiple systems. I'll probably end up asking some specific questions, but I thought a CW style tips might reveal some things I would even think to ask about.

Update: I guess this would also address tips to make upgrading/replacing your development system easier (something I've just done).

So, one tip per answer please, so the 'top' tips are easy to find.

How do you make it easier to develop on multiple systems, or to transfer work after upgrading/replaceing a development system?