(I have first noticed this with MS Office applications, but I have seen it also ...somewhere in Gnome, I can't remember where...)
If a dialog pops up that basically asks you to choose only one option out of single radio button sets (e.g. "Send Response / Do not send response / Edit response before sending"), you can double-click the radio button of your option to dismiss the dialog with that option. Here the double-click works as a macro for choosing option and clicking "OK".
I like this idea because this serves as a compromise between having only buttons (which you can click accidentally) and having traditional radio buttons (which in fact you still have). If applied to certain class of dialogs (i.e. not a critical dialog, nothing but one fixed group of options + OK/Cancel), it can significantly improve user experience.
I wish I would see more applications adopt this behavior (just for the class of dialogs, of course), but before posting enhancements:
Does this behavior have any significant pitfalls or drawbacks? Can it become annoying or confusing? Other ideas?
A nice example of a dialog where this is implemented can be seen on Figure B in this article on TechRepublic.
The typical scenario when using this dialog is when you manipulate data, formulas and styles around, trying to figure out the best layout. If you are not a newbie in Excel, you know what you want to choose already when selecting data.
So being able to dismiss this dialog quickly can significantly decrease chance of losing concentration on the content. There is literally half of operations that require targeting and moving the mouse: instead of clicking the option and clicking OK, you just double-click the option. (You will feel the difference when designing tables.)
Yet the list of options can still be quite long, but well ordered.
Meta-edit: I'm really sorry if I give the impression that I tend to refute everything. I do appreciate every single idea posted or commented here (I haven't down-voted anything here yet). I was planning to give all of you a big thanks as soon as I find the answer, but it's fact that I owe it to you already. I either simply do not agree with everything -or- It does not answer my question. Maybe it's problem with my definition of the question, for which I apologize.