Microsoft Visual Studio Community 2013 is a very powerful development environment, essentially a revamped edition of Visual Studio Professional 2013 which is now available for (mostly) free.
Bundled tools include Peek, Blend, Code Analysis and full C# refactoring, and if that's not enough then there's full access to Visual Studio's 5000+ extensions.
This does make for an absolutely huge product. The tiny installer is just a stub, which took around 2 hours to download and install every feature of the full product on our test PC (this had a basic 8Mbps broadband connection, and would have been much faster if we'd avoided some of the optional downloads).
The end result for us took up 15GB of hard drive space, and added more than 40 elements to the installed applications list on our test PC.
Community does put an enormous amount of power in your hands, though, and the licensing terms are generous, too. Individuals and up to five people within non-enterprise organisations can use it to create free or paid applications, and everyone else can also use it for non-commercial purposes (teaching, open source products).
Microsoft Visual Studio Community 2013 is a vast, full-featured product, and a must-have if you're a serious Windows developer who's also on a budget.