If you already have your data in a structured form in a database like SQL Server, and you want to expose those bits of data (e.g. your customers, their orders etc.), then the WCF Data Services is probably one of the most efficient and productive ways to expose your data. It handles a lot of the underlying goo for you and lets you concentrate on what you want to expose, and what to hide. And it even supports things like querying in the query strings, and inserts and updates quite easily.
If you have more non-structured data, both bare-bones WCF with the REST starter kit or ASP.NET MVC seem to be quite valuable choices. Haven't done much myself with either of the two, but both are quite current, quite productive for developers and should fit nicely in your environment.
So I guess in your position, I'd check out WCF Data Services first and use it, if it fits the bill - and if not, choose between WCF REST Starter Kit (which also works with classic ASP.NET webforms, or winforms, or console apps, or WPF, or Silverlight) - or check out ASP.NET MVC if you're going that way already in your project.