My family and I recently visited Berlin (among other places). While we were there, Andreas Wolff, a Ruby friend, was kind enough to play tour guide for us. Not only did he show us around town, he even played translator in a couple of stores while my wife tried to replace things that she'd lost when her handbag was stolen in Brussels.
Outside of showing us around Berlin, Andreas hacks Ruby, maintains Rubyblog.de (linked above and in my links to the right), and heads up the Rubylation project.
Aren't Ruby hackers great?