put history command onto command line without executing it

To request that the command be printed rather than executed after history substitution, add the :p modifier, e.g. !42:p. The resulting command will also be entered in the history, so you can press Up to edit it.

If you have the histverify option set (shopt -s histverify), you will always have the opportunity to edit the result of history substitutions.

The fc builtin gives limited access to history expansion (no word designators), and lets you edit a previous command in an external editor.

You can use !prefix to refer to the last command beginning with prefix, and !?substring to refer to the last command beginning with substring. When you know what you're looking for, this can save a lot of time over history | less.

Another way to search through previous history is incremental search: press Ctrl+R and start entering a substring of what you're looking for. Press Ctrl+R to go to the previous occurence of the search string so far and Ctrl+S if you've gone too far. Most keys other than Ctrl+R, Ctrl+S, Backspace and ordinary characters terminate the incremental search and have their usual effect (e.g. arrow keys to move the cursor in the line you've reached, Enter to run the command).

Another small one: Alt+#

comments out the current line and moves it into the history buffer.

So when you're assembling a command line and you need to issue an interim command to e.g. find a file, you just hit Alt+#, issue the other command, go up in the history, uncomment and proceed.

You can use magic space to expand history before hitting enter. In your .inputrc, map space to magic space:

$if Bash
     Space: magic-space
$endif

Now, whenever you type a space after a history specification, it'll be immediately expanded - handy if you want to edit it, too!