Web applications have increased the scope and complexity of web testing.

Performance issues are no longer confined to the back-end.
Web Application Performance

When you think you've understood the rules, prove it with Microsoft's shockingly decent testing tool
Web performance testing with Visual Studio 2008

Cross-browser compatibility issues have produced a plethora of tools and services that display GUI comparisons on multiple browsers - this approach may not be optimal or even necessary.
Cross-Browser Testing via Static Analysis

This website draws on the recent work of Doug Crockford, Steve Souders, ppk and countless others to promote a new approach to web testing.

Useful tips for Test Automation, Management and Reporting, Virtualisation and Test Beds:

Arrays can be useful for holding tables of data in scripts
But Key Value Pairs are better

Spreadsheets can be useful for storing test data and results
Named cells and Add-In methods

But Databases are better
Using Access and SQL Server with TestComplete

And on the subject of Databases,
How about writing SQL commands via ASP.NET in jQuery?

Once again, without the Dot Net
As above, but with mono instead of ASP.NET

After the SQL, MySQL
And one more time without any Microsoft components

Plugging in the LAMP
Same again but lighter, faster and cheaper

Linux vs Windows, Apache vs IIS - or all together?
How this website was built

So many tests, so little time
You can't test everything, so how do you decide?

Oracle Application Server - EPIC FAIL!!!1!!
Testing this makes no sense

Through the looking glass - Am I coding? Am I testing?
Visual Studio Coded Webtests

Down the rabbit hole - Testers writing unit tests?
Visual Studio web testing with WebAii

Bringing it home - Workflow Driven Testing
How WebAii and SQL saved my sanity