There's a slide rule for finding fingering in all keys, called the Finger Finder for Viola, and it's not available through the stores because they felt that only the violin version would sell. The one for viola is available, though, at www.edpearlman.net/fingerfinder -- The way it works is that you look up either a key or a key signature and it displays finger positions for that key in first position, highlighting the root notes, the 3ds and 5ths in colors, and also indicating the minor key root note. It's a visual complement to scales and arpeggios and is interesting for studying how fingerings shift as keys change. It's patented, so it's not something run-of-the-mill, and people have found it very practical to use. Well, that's it. I just wanted to let you know about it, in case you or someone you know would be interested!