As I mentioned before, I'm at a new company, and I'm one of the .Net developers working on Shadows.com. This is all ASP.NET with C#, and we're doing a lot of cool things inside the site. Shadows.com is centered around community tagging, rating, and commenting. It then faciliates searching on the community's tags. With the commenting feature, any page on the Net could be the start of a discussion thread. Tagging allows similar sites to be grouped together.
If you look at my blog: http://www.jeffreypalermo.com, you'll see that I've added an image link on the left and a text link on the right. The image link will take you to my profile page on Shadows.com, and the text link on the right will take you to a shadow page for the current post you are reading. Every page on the Internet can have a "shadow" page, which is a page about that page. The shadow page contains tags, ratings, and comments about the source page, so the shadow page is an extension of my blog post, or any other page.
Most developers don't get the chance to work on an application that gets very high usage, like those on the public Internet, so I feel fortunate that I have this experience.
I'll surely be posting any ASP.NET lessons learned throughout the life of this project. I've already posted some:
Be sure to download the toolbar for IE or Firefox. It'll allow you to tag sites on the fly.