If you're a del.icio.us power user and you use Windows Mobile, you've probably missed the del.icio.us plugin that's available in desktop browsers like IE and Firefox. Dale Lane took this problem as a challenge and coded a nice little Pocket IE plugin that adds a del.icio.us submittal form to the browser's menu.
This is not as trivial as I expected - it took hundreds and hundreds of lines of code just to get a new entry in the Internet Explorer's menu that gets me access to the web browser object as an IWebBrowser2. And (perhaps especially so for someone who has been getting a little lazy with Java and C#! ), some of it is a little intricate and complex.
Still, once done I could use my access to the browser to launch my "post to del.icio.us" form and prefill it with the URL and page name of PIE's current page. From there, the form uses the public del.icio.us API to send all the info off to my del.icio.us list.
It's written in C++ and he's zipped up the full Visual Studio project. Based on the difficulty and lack of great documentation for doing something like this, this is actually a pretty solid find. If you want to make a PIE plugin, this would be a good place to start.