I used to use a HTPC back in 1999 and early 2000's.
For the longest time I had no use for one though.
However, I recently picked up a AppleTV first Gen at a garage sale for $5. I added a graphics accelerator card and installed a custom version of linux called CrystalBuntu.
So,... it's my HTPC. I have all my CDs on there as Apple Lossless Files and my DVD collection as MKV. I don't use popular XBMC add ons ... Just use it as a media server and for that it's PERFECT. (For me.)