Certain web-sites allow users to swap IP addresses easily.

With 3G services, for example, users could swap digital photographs or download movie trailers on cellphones - assuming someone would want to do that.

Sony's Memory Stick is now embedded in most of its new products, so users can easily swap data between cameras, computers and P.D.A.'s.

They have also introduced handsets that operate on upgraded networks and allow users to swap songs, e-mail and other data at faster speeds.

They can help people learn how to find and use information: for example, users swap Web sites and discuss Web sites.

In March 2011, Lensbaby introduced seven optics that a user can swap into and out of any of the in-production Lensbaby lenses.

The free service enables users to swap songs, in the form of MP3 files, between their computers.

When traveling, the user may swap the 'home' and 'world' zones-thereby enabling proper time signal reception on a different continent while retaining the other time.

Kazaa is an online programme which allows users to swap media files over the Internet.

Napster, the service that allows users to swap digital music files, is a perfect example.