Using JMeter, We could do Stress Test on
a) Http Servers
b) Ftp Servers and
c) SQL queries.
JMeter is swing application , where you could configure your Stress Test by giving information like
URL
No of concurent Users
No Of requests etc.
JMeter then spans n threads (simulating the concurrent users) and keeps sending the request to the URL you specified.Once the test is over it gives you a graph how much time each request took. You could get many valuable information out of that graph like does ur system slows down after some time etc
Jakarta does have a user Manual for JMeter
http://jakarta.apache.org/jmeter/usermanual/index.html