Howd do I toggle between 'previous searches' inside intellij, in other words, past 'find usages'?

Whenever you search you have a check box of "Open in a new tab". If you do that then the results aren't overridden by a new search.

Right-click the Find view: there is an item named Recent Find Usages (You can also go to it using CTRL+E when you're in the Find view). Usually, CTRL+E is the contextual way to access history.

Please note that it doesn't save the results, but only the query. In other words, it executes the search again each time you use it.

Also note I'm using IntelliJ 10.5.2, not sure about older versions.