I simply use the 'save for web' option in Adobe Photoshop CS2. You can vary the quality/resolution and/or the measurements of your picture very easily, and you can see the file size change while you do, before having to save anything.
And as the pictures of my new Orion in the Showcase section prove, I still prefer to take bass pictures outside, specifically in the early evening of a bright sunny day, sometimes with, but most of the time without using the flash.
Wilfred