I've seen a couple of request asking you to implement certain arguments when launching specific external programs. I would like to see the ability to add any argument(s) to an external program. This would free you up from researching command line arguments and make the Tools->Launch much more usable for any and all external applications - let the user configure the arguments.
For example; one of the reasons I decided on HTMLPad was because of your Regular Expression capability, unfortunately I am terrible at it. I use Regex Buddy to help me. If generic command line arguments were implemented in HTMLPad, I could run Regex Buddy almost like it was integrated into HTMLPad -- and this is only one example.
Please consider adding generic command line argument capability to the launch external program option.