Instapaper is a great Web based widget for temporarily bookmarking sites you want to read later. I've found that if my Firefox bookmarks get too numerous, they're not as useful.
You drag their "Read Later" button to your toolbar so that whenever you're at a site, you just hit it and it's saved. Later, you go the very minimal Instapaper site, and see what you've accumulated.
This is great if you're following a topic such as the 700 MHz auction and you're scanning a bunch of sites, and eventually want to use material/links in a blog post.
David thinks that others should be able to see what you've collected in the spirit of the folksonomy movement typified by such sites as Del.icio.us, Digg, Tumblr, etc. I don't agree. If you can't synthesize the information you're reading, you're not providing much of a service to your readers.