I end up meeting other HNers when I go to user group meetups, Barcamps, StartupCamps, etc... In most large cities I imagine the same thing happens.

But about your site - it looks fine to me, although I would make the 'cards' smaller and over a couple of columns because it takes a lot of space this way. Also, I'd make the "Location" a field rather than something you put in the description because it's going to get difficult to find a relevant entry very quickly.

If the hacker lunch idea doesn't work out, you can turn it into a hacker friendly cooking/food site for lunch ideas. :D