Scott Hanselman recently posted about some truly wonderful tools for working with Multiple Monitors, and putting your laptop to work while in the office.  His post can be found here:

http://www.hanselman.com/blog/PermaLink.aspx?guid=fbf0b95f-3fb4-4d46-ac71-8b3158895dad

I'm really thinking about getting UltraMon right away, and the MaxiVista virtual display driver may follow shortly there after.

How many monitors do you think are optimal for development?