social bookmarks manager; allows you to easily add sites you like to your personal collection of links, to categorize those sites with keywords, and to share your collection not only between your own browsers, but also with others.
collects the link structure of a website. Data import/export from/to database and CSV-files. Export to Graphviz DOT, Resource Description Framework (RDF/DC), XML Topic Maps (XTM), Prolog, HTML. Visualization as hierarchy and map.
a command-line for the web. After setting it up on your browser, you simply type "gim porsche 911" to do a Google Image Search for pictures of Porsche 911 sports cars. Type "random 49" to return random numbers between 1 and 49, courtesy of random.org. And
a list of 50+ similar services that are absolutely free and require no e-mail registration to use. Included in the list are file size limits, download limits and the amount of time the file remains on the server for download.