The best choice of tools tends to vary quite a bit from one developer to another. It's also very dependent on the details of the type of application you're building.
For me, Visual Studio Team Suite is indispensable. It has a rich set of visual designers and other features that have a big impact on my productivity. Deep integration with bug reporting and source control is another huge time saver (I use Team Foundation Server).
With web forms, you can of course often use drag-and-drop components, which improves productivity for some people (although not me). I can't say I'm a fan of most third-party components. They can be quirky, take a long time to learn well, and then still not do exactly what I want them to. It's also a skill that often isn't portable from one job to the next.
You can leverage jQuery to help simplify scripting -- although even with jQuery I find scripting to be one of the most time-consuming and error prone aspects of web development.
If it's suitable for your environment, you might explore Silverlight. That way, you can often have the best of both worlds, building desktop-like apps using desktop-like tools, but with web-based deployment (Expression Blend is an awesome tool). You can also use Silverlight as a replacement for JavaScript in many cases, with code that's compiled and type-safe.
Good tools on the data side are critical, such as SQL Server Profiler. Visual Studio Team Data (part of Team Suite) is invaluable for it's data generation, unit testing and deployment and management aspects.
Something very underrated by many web developers is building up an appropriate infrastructure: things like logging and performance counters, that can help you track down problems quickly when they occur. A solid configuration system is also important.
In case it helps, I put together a longer list of tools. I also write about something I call the "ultra-fast approach" in my book, which is about more than just building web sites that run fast; it's also about how to build them quickly and reliably: Ultra-Fast ASP.NET.