First is Dropbox. I've been using Dropbox for a few years now to sync files between my various computers, and it works great for that. What I've been playing with a lot lately is the Public folder. Anything you put in that folder becomes available to other users or devices via a easily copied URL. You can use that URL both as HTTP and HTTPS, and it seems to support a wide range of content types without problem.
My best practice is to put things in subfolders of public with not-easily guessable names. All the URLs for public items look like http://dl.dropbox.com/u/
To make it easier to get to those URLs on my devices, I tend to use bit.ly (or it's shorter version, j.mp) to turn the long URL into a short opaque identifier.
A second useful tool is one I just started using last week: http://jsapp.us. I think of this as an equivalent to our own Ares tool, but for node.js server apps. You get a Bespin-based code editor, some file storage, and an easy way to run your node code on their services. You wouldn't want to make giant systems with this, but it's great for writing a 20 line script to test out HTTP error code generation or user authentication methods.
A final tool that I find myself using almost every day is our own Ares Debugger. If you're doing anything webOS and haven't tried it, please go to http://ares.palm.com/AresDebug and try it out. It will suck the JavaScript right off the device or emulator, let you set breakpoints, single step, and inspect variables.
