Both of these tools are useful in finding contacts as well as developing and maintaining your relationships, and so are useful for the types of work that ACT! users like to do. I fact, I believe both of these would be great functions to add to ACT! itself.
Xobni is an add-in that indexes your Outlook data and then provides a number of useful functions:
After you install Xobni, your system may run slowly for a day while it creates it’s index. Do not be concerned by this. Once it has completed the index it will speed up your day.
Note: If you’d like to see Xobni create a link to ACT! by Sage, please add a vote on this post on the Xobni Community Site
LinkedIN is a business oriented social network. Their Outlook add-in is a powerful resource for building and maintaining your network from inside your email system. Functions include:
ACT! users should also join the LinkedIN ACT! Fanatics Group
Both of these outlook add-ins are free and Outlook users should give them a try