Since Banshee is working to be the Linux version of iTunes (albeit with many, many improvements due to its open nature), I think one of the most important features that could be added as an option, either through extensions or simple as a general option for the program as a whole, is automatic sorting strings.  iTunes automatically sorts out articles - A, An, The - as well as symbols such as quotation marks, parentheses, and so on.

Banshee could build on this.  When you select the "ignore articles and symbols and sorting" option, in the track editor (perhaps under Extra), there will be a drop-down menu for supported languages in the article sorting.  It will assume that English is the language for tracks unless told otherwise, and users can go and change the track's language.  Then, banshee will create sort strings for name, artist, album artist, and album according to the articles of that language.  For instance, if a track is labeled as French, it will ignore Les, L', and so on.  German would ignore Der, Die, Das - and it goes on.  Of course, regardless of language, starting symbols are taken out of the sort string.

This would not be terribly difficult to code, and for those who don't wish to sort this way (I can't imagine terribly many who wouldn't), it can simply be turned off as an option, or not used as an extension, whichever way the programming goes.