Whats messing with my groove today? The organizational ability of modern operating systems. Pretty much the only way to organize stuff is via drives, folders, and naming. What would be nice is a group or divider of sorts, that way I can divide a folder up into organized and labeled sections, yet keep the contents visible and easily selectable. For instance, completely unrelated to what I'm doing, you have some photographs from a series of vacations, and wanted to organize them by both vacation and individual sections of that vacation. Currently you'd have to do something like:

EuroTrip 2010
├ Spain
├ Italy
├ France
├ Germany
└ United Kingdom

Then in order to browse through them later, you'd have to access each individual folder before you could view the contained images. If we had some better organizational method, you could have a folder labeled EuroTrip 2010, grouped divisions labeled with each country name, and the ability to view all of the images at once without having to drill down into folders, and back out of them, while still keeping things intelligently organized. In real life they have dividers for binders and folders, so why not for operating systems?

Edit: In Windows 7 you can organize by groups, which in fact function like how I'd imagine the above to operate, but you can only group by things like date, file type, and a long list of other things, but this method of grouping relies on preset values, or editable values that an individual file type may not possess.