Bookmarklet is a very important piece of my development. Lately, I've been using the following:

1. ReCSS

   Super B tool, used to reload your css without refreshing the whole page. It's very useful if you want to change a website in production that you can't run locally.

2. Firebug Lite

   

   If you develop websites in different browsers like I do (webkit nightly build), and can't live without Firebug; Firebug Lite is the way to go. It isn't as powerful as the Firebug add-on but it does a good job if you need to use the console or check for applied styles. Unfortunately, there is no way to change the css on the fly.

3. Design

   

   A very cool set of design tools. It includes grid, rule, unit and crosshair. A must have if you are designing in the browser.

4. jQuerify

   As expected, it includes jQuery to the page. Very useful if you want to use firebug's console and jQuery selectors.

5. Favelet Suite

   If you are a fan of the web developer toolbar add-on for Firefox, you will love this tool.

6. xRay

   It displays CSS information of a selected object.

7. Microformats

   

   Every time I markup a page, I try to use microformats as much as possible. This bookmarklet gives you a list of vCard on the page. Unfortunately, it doesn't display any other micro data.

If I missed any other bookmarklet, feel free to leave a comment with the link to it.