You can adjust the Micrometer applet by drag the slider or drag and drop with your mouse.
However, you can only change in a finite range.
Because I am not good at drawing, so I use one of the image file for micrometer from the web.
However, I was not able to use full range setting.
May be I can create another applet similar to one of the [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=502.msg1897#msg1897]flash animation[/url] at the same page.
I really hope that there is an applet on how to read positive or negative zero error for faulty micrometer screw gauge and vernier caliper.
Do you mean a non-calibrated micrometer or vernier caliper? (The reading is not zero when the distance is zero)
It will never be too much as long as the suggestion can lead to better teaching/learning for physics. :)
I am writing another applet to include the feature you have requested. I will post it when it is done.