One more service that I have started using for a bit is Evernote. Evernote is a tool to archive items and works as a web application inside many browsers including Firefox and Safari. Additionally there are Windows and OS X clients. Using the web interface, one can cite web pages, adding keywords for later retrieval or merely add content through cut and paste. Using the client, one can cut and paste rich text and/or images. Evernote will keep these items (including OCR the images) and allow search retrieval based on text search or keyword hits. I have 92 items stored here at this point having been using it a bit over a month.
There is an interesting iPhone version that I have not played with (since I don’t have an iPhone).