http://mobitest.akamai.com/
Mobile performance testing platform from akamai based on the webpagetest.org infrastructure, free. Useful.
http://20bits.com/article/statistical-analysis-and-ab-testing
A good introduction to the statistics math of split testing.
http://abtester.com/calculator/
Includes the math behind the calculation, and sample PHP code to actually generate the numbers. Very cool.
http://blog.asmartbear.com/easy-statistics-for-adwords-ab-testing-and-hamsters.html
Simple formula to calculate statistical significance at 95% on AB / split tests. N = total clicks, D = diff between win & lose, if D² > N, it's statistically significant. Example, 14 clicks A, 22 clicks B, N=36, D=22-14=8, 8²=64>36, win. If 2D²>N, 99%.
http://www.keywords-consultants.co.uk/
Link from Dafydd. Interesting business offering cost per acquisition based online marketing services. Worth pursuing at the relevant time.
http://unbounce.com/
Create landing pages, starts from $25 a month for 1'000 unique visitors up to $500 a month for 100k uniques. They better generate conversions at those prices!