On my iMac, I have photo editing software (that I am not entirely thrilled with), movie editing software (which does have a lot of great features) and software that makes MP3s. Oh, and iWork, which includes presentation software.
There are lots of programs that create content online though, and they fill wonderful, specific niches.
Bitstrips allows non-artists, like me, to makes comics. This is handy for ESL teachers, again, like me, but also for people who simply like comics. I have used it a little and find it still takes time, but the results are so much better than what i would make holding a pen in my own hands and drawing.
Xtranormal creates movies based on the text or script you give it. The computer generated voices are so much better than I recall from my Commodore 64 days.
A cool site I just found today is screenr. You prepare by opening various windows on your computer. Screenr is something like taking 'screenshots' and adding audio, although the effect is not stills, but video. This looks great for making 'how-to' videos.
This site, remixgalaxy, looks like a place to make MP3s. I am not musical, but I do make podcast-type audio fairly often for students.
Since I finished my introduction with presentation software, let me finish the post by mentioning Google Docs and their simple-but-useful presentation option.