QUOTE(simonh @ Nov 8 2007, 11:05)

Also, is there a way of scanning albums to see which one are by various artists?
You can use my
Facets component for this purpose.
1. Set the first Facet to Album.
2. Set the second Facet to Artist (make sure to set the pattern to [%artist%] instead of [%<album artist>%] in the Preferences).
3. Add an "Artists" column to the Album Facet, available in the Statistics submenu.
4. Sort by the Artists column in descending order by clicking on the column header twice.
5. Now you can easily select all albums with more than one artist.
QUOTE
(...) is there a quick way to check that all albums have album gain applied?
Enter
%replaygain_album_gain% MISSING into the Facets search box to display all albums without album gain information.
You can do the same in the Album List's Filter field.