JAMon API is a free, simple, high performance, thread safe, Java API that allows developers to easily monitor the performance and scalability of production applications. JAMon tracks hits, execution times (total, avg, min, max, std dev), and more.
JAMon summary web page that shows page hit stats
N most recent exceptions
N most recent queries issued via JAMon JDBC proxy Driver
Snapshot of jamon page which shows things being measured