MySQL usage profiling?

[Deomid Ryabkov]

the question is simple: how do i know who (of more than 4000 users) uses my database server the most?

the server is a backend for our webhosting services, which means that i know absolutely nothing about applications our users run.

server is becoming quite busy, cpu utilization is starting to reach 100% on regular basis.
however, i suspect that of those thousands there might be a minority of "abusers" that use the database in some perverse way bringing the server down :)
the question is, how do i know? i can have a snapshot of current queries (processlist) and a cumulative statistics (status), but that (at lease to my current knowledge) is all.

i'd like to have just two simpe figures:
1) queries per user and/or per database (most of our users have only one database anyway)
2) time spent processing this user's requests (or time spent processing requests to this database)

i might be wrong (i'd be glad if i would), but there is currently no such profiling facility build into mysql.
if there is a way to get such statistics without hacking code myself, please tell me before i dive into the source and start wreaking havoc :)