The Early Access Program for ReSharper v4.5 just started and nightly builds are available for download. Keep in mind that these are not official beta releases, but automated builds straight from the development branch. The current release has a few very useful features as well as performance and memory optimizations.
Solution-wide analysis has been updated with unused code detection that will highlight unneeded code segments throughout your solution. If you have a layered architecture with multiple solutions you will have to up a new solution that includes all your projects for this to work correctly. If you are doing some Christmas cleaning you may want take these new bits for a spin. It also features a much more flexible naming standard configuration.
Download here.