I think "Alternate IDEs? or how to get more from the standard IDE ?" is a good question.
Like most people here I feel the IDE is great to get started. I'm coming from a software developers world and I would not have become a Arduino fan without the IDE.
The greatness of the IDE to get started also limits the IDE when you are doing library development or have 10+ files in your project. Therefore I also looked at alternatives.
"Alternate IDE's?" Coming from a windows world I only know "kind of" 2 alternatives. I know visual studio and I know Eclipse. Talking about these tools without the plugin for Arduino. In my mind visual studio beats eclipse by far. But they both beat the Arduino IDE from a developers point of view by far.
From a financial point of view Eclipse is free. The visual studio express is also free but does not allow plugins. Visual studio professional is not free (today 999Euro in Belgium
As I can buy plenty of arduino's for that money I looked into the eclipse possibilities.
I find the eclipse + "avr eclipse" solution -described in the playground- extremely powerful but also to complex. The main problem is that there are so many options that you don't know which are important nor how to set them.
So I decided to write a plugin on top of avr eclipse to set Arduino settings to make it easier to get started. I released a version some time ago. If you are interested please read this article on usage and installation http://arduino.cc/forum/index.php/topic,70547.msg589022.html#msg589022/
it is 100% free and the source is available like Arduino.