Selenium IDE is great for recording and running tests. However, running recorded test suites using Selenium RC is better.
I had an issue today where results weren't being generated after executing:
java -jar selenium-server.jar -htmlSuite "*firefox" "http://url" "/path/to/testsuite" "/tmp/results.html"
Turns out the test suite and tests must have the .html extension. Googling helped me to find the answer in the comments of this blog post.
java -jar selenium-server.jar -htmlSuite "*firefox" "http://url" "/path/to/testsuite.html" "/tmp/results.html"
The generated results are excellent.