Yes, I find using online programs very convenient. I use Keepvid to download videos from Youtube, and I use flash games to entertain myself. When I need to write something, I log in to Google Docs. I don't have to check if the program will run on my PC, download, and install anything on my PC. I only find the logging in part kind of inconvenient.
I spend so much time on Facebook, and other websites using their online apps.
i don't really download any music any more, as i can find most favourites for free on youtube, spotify etc. and occasionally i play some flash games. graphics programs are really the only ones i need to download.