O&O RegEditor is a handy Registry editor with some useful bonus features.
The program is portable, making it very convenient to use. Just unzip the download and launch the 32 or 64-bit version, depending on your needs.
Basic navigation is just like REGEDIT - hives presented in a tree on the left, browse to a key and its values are on the right - helping you feel at home right away.
Editing is improved. In REGEDIT, double-clicking opens a value in a separate window and you can't do anything else until the edit is complete. In RegEditor, double-clicking displays the value in a panel, and you can continue browsing the Registry in the main window - great if you need to refer to some other key first.
You also get full copy and paste support, with the ability to select one or more keys, copy them and their subkeys and paste them somewhere else.
The best feature is probably the search. Its core options are the same as REGEDIT - no regular expressions or anything advanced - but instead of jumping to one match, then the next, it displays them all in a single panel. You can then scan the list, double-click anything interesting to jump straight to that value, or process multiple values all at once (multi-select, click Delete, for example).
There are other bonuses and extras here, though probably not as useful to most people. (Do you care that RegEditor can export the Registry to XML, for instance? Thought not.)