ID:133644
 
Not sure if it's called a tool tip or not. Anyways, I would lvoe to see a little help box pop up as you're typing in a function name that tells you all the parameters of a function. I've seen it done in a few languages.
This is called intellisense and it's been suggested and shot down before. These kinds of things are more ideal for user-created IDE's and not the official one, it just takes time away from more important development.
In response to Nadrew
I recall OFD making something in AutoIt or AutoHotKey to do this, search around on the forum.