I've been following Pi folks since it came out and there are a range of people from those who pre-ordered to those who got one only as the result of a gift.

Pi's are good for teaching you things, so if you got one you would learn with it. A number of folks have started learning about Linux system administration with theirs after being somewhat 'light weight' in that department. Others are learning about new programming languages or environments, from node.js, to R, to Scratch, to python. Getting Docker on them has had people setting up server deploys. Running web servers have people creating small web sites with bootstrap and other technologies.

But if you really aren't interested in learning those sorts of things, well its not really very useful. Everything it does can be done 'better' in a production environment by a server, usually x86 based, designed to do what ever it is it is doing.

Bottom line is there are a lot of things an RPi can help you learn by giving you hands on experience. If you're not interested in learning those things, it probably isn't all that useful.

Here's what I use mine for:

> Hosting my website (with CloudFlare in front)

> A gateway into my network (almost all ports are open to the RPi including SSH). I can ssh in and then every device on my network is configured to accept connections from it. Hitting my devices directly (over v6, for instance) would be rejected by firewalls and such.

> Personal Cloud: I use BitTorrent sync to move files around my computers. Sometimes my desktop / laptop aren't on at the same time. I solved this problem by putting BTSync on my RPi. It's online 24/7 so my files are always accessible.

> MySQL server (for development).

Ideas I have floating around:

> Possibly hosting my email

> Internal services like Squid caching.

> Server-Side Development. It's a tight environment (ram is limited, cpu is fairly slow) so it forces you to build lightweight programs. If it can run well on a RPi, it's probably fine on a VPS.

> Monitoring/graphing uptime/latency -- My router doesn't do this for me.

> Scheduling backups (possibly via rsync?)

Your RPi is basically a home server. Use it to control devices in your house and do automation.

Log temperatures in your apartment/house: http://thule.mine.nu/html/

If you like games, check out the RetroPie project. I just finished mine yesterday. I've got the entire NES, SNES, and GBA rom sets on it.

Aren't you putting the cart before the horse? The Pi is a great tool for solving problems; if you have something that needs automating or you need a small computer for, you can buy one and it's relatively easy to make it do what you want. But it's a means to an end, not an end in itself.

Get some GPIO breakout boards, and turn things on and off, read sensor values, and make an internet of things. Get some relays and learn how to turn off your TV/Sound System when it's not in use to save some power. Or control some christmas lights.

Run a Tor node (as per my other comment).

I use mine for a fermentation temperature monitor/grapher, and another for a squeezebox client.

If you're a kinkster there was a "What do you do with your Pi" post on reddit a while ago, and some guy basically programmed it to fuck his wife - the joke of course being that a true hacker will attempt to automate everything, including romance.