I tinker often with external webpages and sometimes miss having jQuery available there. Then I use the following link as a bookmarklet, which just loads jQuery into the active page:
Right click on the button above, add to your bookmarks and you’ll never have to go on your explorations without jQuery on Chrome.
If you have a Bookmark Toolbar, then you can just click and drag there as well.
Note: Doesn’t work on Firefox 29.
How it works
It executes the following code on the active page:
This fetches and loads
jQuery on the page.