In the minibuffer,
M-p (previous-history-element) is useful, but I find
C-r (isearch-backward) to be even better, as it lets me recall a specific history element without going through them one by one.
When using isearch outside of the minibuffer (in the main text area), I can hit
M-p at the isearch prompt to run isearch-ring-retreat, which pulls up the previous search string at the prompt. But I might be looking for a prior search string farther back, do it would be nice if I could use isearch to search the search-ring itself.
Is this possible?