My editor of choice for most of what I do on the Mac (when I’m not in the shell using Vim) is Textmate. I recently came across a neat plugin called the Textmate Minimap. Essentially this plugin opens a map across the side of your Textmate window (like another drawer on the other side) and allows you to scroll full screens. You can move the editing window screen by screen in the minimap. This is equivalent to a visual page down.
This isn’t really handy if you have a lot of small files, but you can imagine the utility with larger files. Now its still in beta stages, so be weary when you try it out. Install it into Textmate as a bundle and use it as necessary.
