Just what I was thinking too
Sepia would be very nice for that "old school photo" kind of look. This feature is great. It could really go places. Being able to do the auto optimize thing would be very nice. I have a prog which I use to view photos that came from the site dot photo which allows this and it is pretty cool. I also use ACD FotoSlate when printing contact sheets and this allows auto optimization just for the print without affecting the orginal file. very nice... with a way of doing this and saving the copy this would be awesome...
Are you looking for ideas of other filters that could be added? A nice one may be to add some kind of mask to the photos to give it like a border. You can do this with photoshop but then the change is permenant. If MC could do this on the fly that would be very sweet.
A lot of cameras also have a negative option. Personally I never saw the use for it but someone might want it...my sony DSC has a solarize option as well. Again I never really saw the use but...
If I think of anything else I will post but I definitely think the border option would be nice and would be quite popular.
Adam