Historians have often been accused of being behind the times in terms of digital applications. This may be true in some instances, who hasn't seen a historian fumble with a simple PowerPoint presentation. However, there are also a number of historical organizations and professionals who have embraced various forms of technology. Many of these technologies are focused on making tasks easier, including the trouble and cost of long distance communication.
One of the simplest communication focsed applications is Skype. Skype is free software that allows you to "talk" to anyone else who has Skype without a charge. You can also pay a nominal fee to use Skype to call land lines. Providing you have high speed, this is a very economical choice in lieu of long distance calling.
In addition to Skype, Dimdim is a great application for long distance group projects. Having a problem with a program? Want to share ideas? Dimdim allows you to share screens, so you can easily compare work, which ideal for anything involving groups. Dimdim is frequently used for web conferences allowing for a more open sharing of ideas than a mere conference call.
I was also recently exposed to near-time. This application is a file sharing, collaborative workspace. It is very similar to the collaborative nature of a wiki and hosts many similar features. Near-time is a bit more ascetically pleasing than the average wiki. However, the major near-time is not an open source application and may not be a practical application for many smaller organization.