Website Stress-Testing
Useful article including whys, how-to's and reviewing a shortlist of software to help.

The quest for a 3 row "letterbox" style layout
These are my notes on vertically stretchy layout tests and prototypes, written a little while back while working on the new frogdesign.com site. Later design changes made a lot of this redundant and/or overkill, but it was a great voyage of discovery for me, driven by a faith that CSS could win the day (in which I think I was vindicated).