I just pushed imeitool to my Github. imeitool is small utility that can do few useful operations on IMEI numbers. It can check if number given is valid IMEI number, find information in its databases about given IMEI or TAC (Type Allocation Code, usually first 8 digits of IMEI) and generate fake IMEI based on conditions provided by user.
The reason this program was created should appear on blog soon. There is a possibility for anyone to contribute to imeitool’s db, so if you want to help, more info can be found on project’s README file.