I've downloaded the nightly build of Resharper and I saw one of the features I wanted for a long time now, Code Analysis per solution. Very nice indeed, only it shows me only the errors, not the warnings and suggestions. I would like to be able to search for those as well.
Also, in my fully working project I found 16 errors, which were all linked to the control ID of web controls. The Asp.NET AjaxToolKit has a few controls that add behaviours to other controls. They are able to find their targets, but if they exist only in the context of the adapter, not of the page, Resharper shows the IDs are erroneous. Same thing with controls that have the same ID but are the children of different parents.