My top seems to act a little strange (running Snow Leopard). It doesn't respond to the key commands I'm used to, e.g. for sorting on Memory Usage etc. Nevertheless, this is how I found out (by chance really) how to kill a process from within top.
First start top using sudo:
Press shift + s. This will promt for a signal. Enter the word 'kill' (if not already selected). Hit enter. Now top prompts for a pid. Enter the pid of the process you want to expedite. Hit enter. Good bye process.