Two must-have Palm tools. First - if you're sick of how limited AvantGo's channel selection is then use a combination of Plucker and Sunrise to download RSS feeds and turn them into Palm Plucker documents. Note that Plucker is open source and cross platform so you can get Plucker readers for many different systems. Sunrise is Windows only but its pre-cursor JPluck is still available for other platforms (its primarily Java based). Second - if you need a quick way of getting images and text into your Palm then use a free piece of software called Vikao. Vikao is a two part application - one sits in your Windows tray and allows you to select any text or image in the clipboard and convert it into a Vikao document which the Vikao Palm application can display.

One of my favourite Mac applications was Frontier - its now been open sourced and modern ports for Mac and Windows (including source-code) are available to download. Its currently at v 10.a1 and it needs a little work but the basics are still there. To give you an idea of what it can do - you can use it as a scripting environment (Frontier existed before AppleScript), an Outliner (Dave Winer wrote More/ThinkTank) and as a Web Publishing System (the underlying Frontier engine is used in the commercial Manila CMS).

This caught my eye - NX seems to offer Citrix/Terminal Server style functionality to Unix - utilising much much less bandwidth than X-windows. A nice overview of its features is available here.

Looks like a nice tool to keep data synchronised between two machines - Unison.

Some nice CSS styles - based on Magazine layouts.