There has been a question regarding iPhone versions of Srila Prabhupada's books, in a comment to our article Cell Phones and Bhagavad-Gita. When the question was posted I was travelling without regular internet access and couldn't find the answer, which has been posted on the Google group World Sankirtan some time ago: KC books on iPhone 3G (version 2) by Candidasa Prabhu (personal blog). Here is the forum post with download links:
Skype is a relatively new and extremely popular technology. It's different from other VoIP (voice-over-internet-protocol) networks as it doesn't rely on central servers, but establishes a peer-to-peer network, which can easily grow with the number of users connected. [Lots of additional information is available here: http://en.wikipedia.org/wiki/Skype.]
The software and basic membership in the Skype-network are free (see download-links in the side-bar), allowing over 100 million users free chat-, audio-, and video-calls over the internet. This includes text-based group-chat with up to one-hundred, and conference-calls among up to ten participants. Another interesting (free) feature is Skypecast: groups of up to one-hundred members can be hosted, in the form of a lecture (one person talks and the others listen), or everybody can talk (or chant) simultaneously.