Allow me to recommend Markdown

John Gruber and Aaron Swartz's Markdown is a plain and open tool for making blogging and other webby things easy and fun. It lets you represent the most common HTML tags that would be used in day-to-day web writing as intuitive punctuation. For example, instead of linking to Markdown by writing

<a href="http://daringfireball.net/
         projects/markdown/">Markdown</a>

I write

[Markdown](http://daringfireball.net/
           projects/markdown/)

I think the simplest way to use it on a Mac is to copy Markdown text to the clipboard, then run the following script:

#!/bin/bash
pbpaste|~/handyscripts/Markdown.pl|pbcopy

A marked-down copy of your text will then be on the clipboard. I pop up Launchbar to call the script in a jiffy, and using a clipboard with history helps manage the whole mess.

SizeUp

Allow me to recommend SizeUp. It's a Mac app that lets you manage your windows without using a mouse. It's super-cheap, you can name your price, as low as $3 for a license. There's a free demo. I use two monitors, and use SizeUp to bounce windows from one to another. This is very handy when I'm writing on my primary screen and have a reference or figures on the secondary screen. I love being able to put windows side-by-side, pixel-perfect, in just a couple of keystrokes.

I think the most pedantic use I have for SizeUp is that I don't want my maximized windows to go all the way to the dock, I want to leave a strip of exposed desktop so that I can bounce files around easily. I don't like thinking about where to save files when I save them, I save everything to the desktop, and then file everything a couple of times a week. This way, I don't hit speed-bumps with thinking about organization when I'm doing creative work.

Also, I keep my dock on the side of the screen. Rows of about eighty characters are optimum for readability, so I prefer tall, narrow windows. Most apps don't respect that, but SizeUp obeys me and beats unruly apps on my behalf.

SizeUp lets me resize and position windows automatically so that I don't have to fiddle a lot.