Weekend Learning: Collecting information to troubleshoot SQL performance problems

Have you ever run into a situation where SQL is not performing like it should?  We have a lot of tools now compared to "back in the day" (before Oracle Enterprise Manager) but some of the classics can be found in MOS article "SRDC - How to Collect Standard Information for a SQL Performance Problem" from note ID 1594386.1 and even if you do not need to work with Oracle to help solve the problem you can utilize these tools to diagnose and possibly resolve it!