For the past three years, I have been suing Mempad on a daily basis both at home and at work. While some parts are not initially intuitive to use, its portability, small footprint, and basic features make it my all-around usability tool. For awhile I missed not having Rich Text, but in the end the features I am about to list more than make up for it, and my rich-text tree tools are lingering on the sideline.

Temporary notes: If you have a node with the current year (e.g. 2009 or 2010), {F6} will create a branch beneath it for the month and day (today, it created December, and below December it created 20 Sun). Phone messages, quick notes, urls, etc. are placed here. {F5} Time Stamps it. It is kind of like a diary.
Launcher: My organization has an official document structure, and lookup is sluggish and painful. By highlighting the document number, and pressing {F8} I get a bunch of preconfigured tools and I choose the one that opens the document. I have other common tools and apps that I run that way.
URLS and files: URLS can be double-clicked. Files as well. I keep bookmarks in Mempad, and if in my default browser, double-click them, and if in another browser, run through the Launcher.

By assigning one Mempad file to work and another to home with shortcut keys, it is ever at the ready.