From Pocket Science:
You can see how many appointments you have, how many to-do items you must attend to and how many emails are left to read and send. you can also see actual descriptions for appointments and to-do items in a simple list format. Works with the major scheduling and email applications (Datebook DateBk, ActionNames, Mail, MultiMail, Eudora, Mail+, Treo Mail, Clie Mail, Iambic Mail, Mark/Space Mail, VersaMail, SnapperMail, BaseJet, Electric Pocket). Displays the number of relevent records, launches the currect app when you tap and where possible displays the correct record. Can be set to automatically launch when you turn your Palm on (after a defined period of inactivity if you like), and to be launched when you press the Datebook button.
The latest version also includes SMS functionality - integrating with Palm's SMS application, Monkey Messenger, Mark/Space's PageNOW and funSMS.