I've been using two outstanding applications with my comparatively ancient Treo 650. The first is a new version of Directory Assistant, now called Tryda Directory Assistant. The application is free if you don't mind giving the developer your contact information. One great feature the new version has is a direct tie-in to Google Maps, also a free download for the Palm OS. Tryda Directory Assistant lets you look up phone numbers and dial directly from the application. It can also find business of a particular type in any given geographic area. Another new feature is reverse lookups. Just enter the phone number and Tryda DA will find the name and address. Enter the address and Tryda DA will find the phone number for you. It also provides driving directions. This is an essential application for the Treo.
The second great app I've been using is GoogHelper by Iambic. It costs only $4.95. GoogHelper helps you quickly launch various Internet searches using mobile friendly sites such as Google, Yahoo!Finance, Amazon, Wikipedia and several more. It's simple user interface eliminates several screen taps when initiating a search. In addition to its web searching capabilities, now you can receive immediate results via SMS/text messaging by using the integrated Google SMS function.
If you are a mobile lawyer who often needs information on the go, add these apps to your Treo.