Ubnutu/MySQL - Error "Unable to locate package innotop"
It seems to be in the file list for mysql-client-5.5.

sudo apt-get install mysql-client-5.5 should be all you need to do.

Note that the mysql client program is in a separate package, mysql-client-core-5.5, so it's possible to have mysql installed without any of the other useful tools like mysqladmin or mysqldump.