I'd like to suggest that the text fields wrap around instead of truncating the text, when the columns are resized.
This will break the nice neat one line displays, but legibility will be improved for long titles and album names.

Currently, each songs must use the same height in a SongList or SongTree, changing that would make loading them much slower, as it would require determining the height of each song, or finding a way around not knowing the exact total height.
But you can have, for example, 2 lines for each song, creating custom columns that display the album name or title using always 2 lines shouldn't be too hard (not completely sure), not sure it would satisfy you, if it does I might give it a quick look.

I think that 2 lines would be sufficient.

Absolutely Awesome support.

This does not wrap text, but it allows you to use shorter collumns by displaying information in two lines. I think this is what squentin talked about: