Geekhack is great because it brings together geeks. For once, we can discuss any esoteric tech-and-gadget related topic we like, and find similarly interested people to share their thoughts and experiences.
I am not even technically trained. Yet in this forum, I have learned much, and gone on to do some soldering and wiring which I have never done in my life.
This forum is best for sharing information and education. For learning and experimenting. Geeks love talking about all kinds of weird and interesting tech trivia, and introducing other geeks to their inventions, adaptations or improvements.
Thanks to geekhack, I can just log on when I have a monitor problem (as I did recently) and ask a question, and within 1 hour get several informed replies. Thanks to geekhack, I've met people who are happy to help me customize my keyboard just because they love tinkering. Thanks to geekhack, I have also done lots of small favours to people whom I've never met in my life or even seen photos of.
I think this website has brought out many good qualities in us geeks, and also encouraged us to communicate with other geeks all over the world. We have people living in obscure Russian cities now surrounded by vast expanses of snow, and we have people from Brazil and South Africa and other sports-mad societies where a geek will normally not get to meet fellow geeks. I can't imagine life without geekhack anymore - it feels so much more boring.