Right now I'm in the Athens hackerspace. What's that? It's a semi-subterranean space, set up by some dedicated geeks, hackers, tinkerers. It's being used for all kind of open source projects, both in software and hardware.
The first time I came here, I walked into the middle of an impromptu lecture on mail and DNS. One seasoned system administrator explaining stuff to some other peeps. Other days there are events for all kinds of more or less open source related groups.
Today there are just some people banging on their laptops and discussing some internal projects. Myself I'm working through a tutorial, and listening with half an ear to any topics that might be interesting.
On the hardware side, there are some tool benches and even a Makerbot. In fact, there is another, different 3d printer in the process of being assembled too. I'm not too much of a hardware hacker, but this stuff is definitely interesting.