Japanese have developed an interesting Firefox extension Wired-Marker.
It is very useful for me as it operates using slow internet ( I use such in the village).
“Wired-Marker is a permanent (indelible) highlighter that you use on Web pages. The highlighter, which comes in various colors and styles, is a kind of electronic bookmark that serves as a guide when you revisit a Web page. The highlighted content is automatically recorded in a bookmark and saved. To use Wired-Marker, you simply drag and drop the selected sections into a bookmark folder. You can highlight not only text but also pictures, tables, and selected portions of the screen. You can even add notes to the highlighted items.”
Use as an “indelible highlighter” on Web pages
Use as an electronic bookmark
Use as a scrapbook folder
Use as a structural organization tool for information
Other useful functions (export, template creation, image capture, etc)