Reverse Ajax, not unlike DHTML, LAMP, Ajax and SPA, is not a technology in itself, but a term that refers to the use of a group of technologies together. These technologies include:
Reverse Ajax is different from Ajax, as Reverse Ajax is a suite of technologies for pushing data from a server to a client. These technologies are built upon an Ajax framework.

A domain hack is an unconventional domain name that combines domain labels, especially the top-level domain (TLD), to spell out the full "name" or title of the domain, making a kind of pun.
For example the second-level domain (SLD) blo.gs makes use of the TLD .gs (South Georgia and the South Sandwich Islands) to spell "blogs". The third-level domains del.icio.us and cr.yp.to make use of the SLDs icio.us and yp.to from the TLDs .us (United States) and .to (Tonga) to spell "delicious" and "crypto" respectively.

Here are some ways to use Google, Alexa, Yahoo! and Clusty to check articles and other information.
Google found a solution to index the web pages protected by webmasters or owners. "First Click Free" means to allow Google to include your protected pages in the search results, and to provide full access for the text on that page. This way, the first visit is free for paid subscription and other protected pages and does not require a login. The free visitor can be block for the other protected pages or sections.