The Little Tom pistol was the very first double action semi-automatic pistol. Ever.
Unfortunately it didn't do well commercially and Walther took this idea (not the design) and designed their own improved SA/DA pistol known as the Walther PP. Up to the time of the Little Tom, all semi-auto's were SA and not particularly safe with one loaded and the covered internal hammer cocked.
Walther is credited with the design of the first succesfull SA/DA semi-automatic pistol, but it was not the first as many people are led to believe.
As far as the Little Tom, I have little information on in-depth history, serial numbers, or value. It would be best if you had it looked at by a professional firearms appraiser such as the services offered by the Blue Book publisher. I couldn't even give you a ball park figure since I have no information on the pistol.
You can find this appraisal information at their web-site or in the Blue Book itself.
