David Nash

Find all files (not directories) and remove the eXecutable bit. I don’t know what the characters on the end do:
find . -type f -exec chmod a-x {} \;

Make all directories executable to user, read/writable to groups others (good for when the web server is in ‘others’):
find . -type d -exec chmod 755 {} \;

Make all files read/write/executable for user, readable for the group and others:
find . -type f -exec chmod 644 {} \;