I have a 1TB HDD filled with steam games, and a 120gb ssd filled with steam games im currently playing (thanks steam mover). Need to get a bigger HDD for steam, still have 50+ games undownloaded and winter sale is coming!
No seriously, it's about 5 games installed of about 280, just a few Gb right now, with high speed internet there's no point in keeping everything installed at once, not enough room on a small SSD to cover all those games I'm guessing the better part of 1Tb total.
I've got ~150-250 GBs at any one time. About 25-35 downloaded out of 335 total. I keep a number on hand pre-downloaded in case I am interested in picking one up at any particular time and some I can't seem to force myself to un-install like Witcher 2 even though I have finished it.
Planning to Raid some SSDs in a couple of months and will probably need to be more careful with how much is downloaded at a time.