VS2010 Find all references to the project in solution

Easy but dull way: right-click on solution, choose Project Dependencies, choose the first project in the Projects drop down list, and use down arrow to scroll through projects. For each project in Project box look if your project of interested checked in the list - that's most probably will make your list.

Or you can use Resharper for this:

• Right-click on module and choose Find Code Dependent on Module to find all projects which really use this module (this will not show references which exist, but not used).
• Right-click on module and choose Project Hierarchy, then click "Referencing projects" to see all project references

The build-in Project Dependencies command only works the other way, i.e., it finds a given project's dependencies, not projects dependent on the given one—unless of course you feel like selecting each of your 200 projects in turn in the dropdown, and then for each project, scrolling down the also voluminous list below to see if the project of interest is included.

Instead, in the absence of Resharper you can use Find in Files (CTRL SHIFT F) to list projects in the solution that refer to the project of interest: