I'm a bit of a data hoarder so lot of it is just downloaded content from entertainment stuff, to things like programs, pictures, etc, but lot of it is code, dev/test environments, VMs for misc purposes. I also host my own local email and use fetchmail to grab from internet servers. I run my own local DNS as well, and lot of stuff of that nature, basically a smaller scale version of a corporate network I guess. Essentially it's my own little cloud. Instead of using cloud services for stuff I just host it all locally. I also host a UO game server, so got a VM for that as well. Really lot of random misc stuff, that I sometimes forget about myself lol. It just runs and does it's thing haha.
I eventually want to upgrade my VM setup though, right now I use ESXi free which is kinda limited. I'd like to look at something where I can do live migrations and stuff (without the expensive licensing). I know qemu-kvm can do it but there's not really lot of good front ends for it. I think Proxmox is the closest thing. Been meaning to play with it some time.