See: compulsive hoarding.
I don't hoard real-life items at all. In fact I'm quite the opposite. I want my real life to be as light-weight and portable as possible, and therefore I tend to throw away things that other people will still think are useful. In the digital world though, I am quite the opposite. My hard disk tends to fill up more and more and more with unsorted photos, music and videos. When I see a video I like on youtube, I download it. When I listen to a song that I like, I must have it. When I finish watching an anime that I liked I must have everything related to it on my hard drive. It's become quite the obsession.
But what to do with all that stuff? As a proper IT-savvy person I make regular backups of my stuff, and running a RAID 1 mirror on my most vital possessions means that I'm unlikely to lose anything by accident (fingers crossed). Yet over the years I have accumulated stuff that is unsorted, and so messy that I couldn't even begin sorting it. Other things are sorted but I've lost interest in them. Occassionally I find things on my hard disk that I used to like five or ten years ago, but don't have any particular feelings about any more. I used to just leave it where it was, but lately I do try to delete stuff, or at least archive it to another place. I tend to enjoy organizing my 'possessions', putting everything in the right place, trimming it down wherever possible. It's like a little garden of digital goodies.
So yes, I am a compulsive digital hoarder. And I'm perfectly okay with that.