This may not be a tip that's too outstanding for everyone, but I've recently started employing the tweak to help me in my web development tasks. One of the challenges for me in development is that the data source for my web pages may change depending on my location on specific testing need. This tip shows you how to easily manage those changes on the fly.
Depending on the situation, I could be working on the development of a website while working completely off a local copy of the database. Later I may need to point the web pages to a different database for testing that could be on one of the other corporate machines. Lastly, I could need to point the development to the live production server.
I used to accomplish this by having multiple versions of the web.config file that would point to each location. Now instead I add all the connection strings into a single web.config file and then comment out all of those that I'm not using.
I use Microsoft Visual Web Developer 2008 Express as my development tool and I can easily manage the web.config file internally and use one-click toolbar buttons to comment or uncomment out portions of the code.
UPDATE: Microsoft has discontinued their Visual Studio Express product and replaced it with the Visual Studio Community. Here's a nice article from the folks at Spreadsheeto on the change and differences between the two offerings from Microsoft.
Now I don't have to worry about maintaining multiple web.config files and making sure I mirror any changes in one with all the others. Now I just use one file and have all the connection strings available at anytime as needed.