Java ME SDK has an important feature which can speed up MIDlet development. MIDlet can be redeployed into already opened emulator.
After receiving some feedbacks from users of early access I see than this feature is often undiscovered. That's pity because it improves usability of emulator and saves a lot of time spent on emulator restart.
I usually run emulator once without specifying a MIDlet - only to open AMS.

emulator.exe -Xjam -Xdevice:/device name/

and then deploy my application again and again without exiting emulator - just exiting from a MIDlet.

emulator.exe -Xdescriptor:..\apps\myapp.jad -Xdevice:/device name/

Several things happen in background transparently to an user. MIDlet is deployed, launched and after exit it is removed. The same feature works of course also from gui.

-Tomas