Gists are lightweight repositories, so why not take advantage of that?
Clone your gists to a 'my_gists' directory, organized in the way you would want them organized.
Then they become searchable fully using whatever search tools you are familiar with on your operating system.
You also have the advantage of being able to edit, comment, commit and push.
This let's you do all that you have listed and more.
Add git instaweb to the mix and you even have a rudimentary web interface to your gists.
