It introduced volume mixer (which stays kinda beloved and sought out even now) (and also WASAPI), search in start (hit start and type, which is now everywhere), snipping tool (which is made even better in windows 11), etc., there's actually a bunch of features there that either get overlooked or misattributed to windows 7, which is kinda interesting. Check out this article about them https://en.wikipedia.org/wiki/Features_new_to_Windows_Vista