Here is a useful collection of various tools for online marketeers, conveniently classified into groups ranging from usability testing, site performance testing, SEO ranking to web analytics. No doubt that there are a range of other tools that this list missed and therefore by no means this is comprehensive, nevertheless this is a great starting point.
http://www.testing-web-sites.co.uk/testing-tools/
A solid collection of Google Agency Training videos & webinars covering everything from Google Analytics, Google Website Optimizer, hard-core analytics discussion with Avinash Kaushik, Google Adwords API and much more! If you simply want to beef up your online marketing skill-set, this is the place to go!
If you work in online advertising & web analytics and regularly execute campaigns for your clients, this one-stop shop comes in handy.
http://www.google.com/agencytoolkit/
This toolkit basically comprises of tools allocated into 4 major categories:
Plan
Create
Place
Measure
