The xbindkeys-1.8.3 available in the current ubuntu repositories crashes after pressing 7 listened for keys.

Because I have no idea what I'm doing, this advice should be taken with a grain of salt. I make no claims that following my directions won't erase all your data and destroy your computer.

Put the latest xbindkeys tarball in some directory (I like to use $HOME/src)
tar xvzf xbindkeys-1.8.5.tar.gz
cd xbindkeys-1.8.5
sudo apt-get install libx11-dev guile-1.8 guile-1.8-dev guile-library
sudo ./configure
sudo make
Get some error. But just sudo make a few more times anyway.
sudo make install