For a comprehensive list of open source performance test tools please refer here
and for your further interest here are some functional automation test tools
To save you a headache with reviewing all these though. If you are looking for a performance load simulation tool that will support HTTP/HTTPS,JMS P2P/PUB/SUB,SOAP,JDBC,WebServices,LDAP,POP3 and IMAP, then Apache JMeter is your tool. This will be able to drive your load and analyse metrics. You can enhance your metric collection and analysis with other open source tool sets.
Jmeter has always rated highly in opionion surveys. In this May 2008 survey it is listed as the most popular open source performance testing tool Opensourcetesting.org survey and also here in 2009 10 Best Open Source Performance Testing Tools
If you want a more loadrunner look and feel, then OpenSTA comes a close second for HTTP/S load simulation.
I have used both in major organisations in Australia with huge success.