<p>In Google Reader, you can use a bookmarklet to "note" a page you're visiting. When you press the bookmarklet, a little Google form is displayed on top of the current page. In the form you can enter a description, etc. When you press Submit, the form submits itself without leaving the page, and then the form disappears. All in all, a very smooth experience.</p>

<p>I obviously tried to take a look at how it's done, but the most interesting parts are minified and unreadable. So...</p>

<p>Any ideas on how to implement something like this (on the browser side)? What issues are there? Existing blog posts describing this?</p>

At it's very basic level it will be using
```
createElement
```
to create the elements to insert into the page and
```
appendChild
```
or
```
insertBefore
```
to insert them into the page.