JetBrains are also about to include decompiling functionality into their forthcoming release of ReSharper 6. In fact, decompiling has been announced as part of ReSharper 6 back in February 2011, and available in ReSharper 6 pre-release nightly builds since then.
For all features described below, default keyboard shortcuts are specified. By default, dotPeek uses the IntelliJ IDEA shortcut scheme derived from ReSharper. dotPeek also provides shortcut scheme familiar to ReSharper users - that is, the Visual Studio shortcut scheme. You can switch between those schemes via File > Options.
Opening and Browsing Assemblies
dotPeek also provides Go to File (Navigate > Go to File or Ctrl+Shift+N) to quickly open files and folders. However, it is limited to temporary files from dotPeek decompiled code cache, so you can use it as an extended tab switcher that not only works with currently opened code files but also takes into account any tabs that you've opened during the current dotPeek session.
Speaking of previously opened files, if you've recently closed a code file but you need to have it open again, there's an easy way to have it back: just choose Navigate > Recent Files (Ctrl+E) and in the resulting drop-down list, pick the file you're looking for:
Context-Sensitive Navigation Between Symbols in Decompiled Code