The VS2010 Recent Project list is not very friendly about displaying web sites which you are running under IIS Express rather than the ASP.NET development server. It gives them names such as "http://localhost:54890" which are hard to remember for most people.
A quick workaround is to locate the solution file for the project associated with the website using Windows Explorer and rename it to something that is more descriptive, for instance, TheWebSite.sln rather than localhost:54890.sln. Back in Visual Studio, go to File -> Open Project, then browse to and open the renamed solution file. The IIS based website will open and the Recent Project list will now use the name you gave the .sln file as the link to the web site, making it easier to identify in the future.