4mat от OGGrimes

If you work in networking and frequently have to find and cross reference MAC addresses, it can be a pain to convert them manually between different formats,
(eg Huawei's abcd-1234-5678 format to the traditional ab:cd:12:34:56:78 format, and vice versa).

With this add-on, you just need to copy the MAC address into the input field and then select which conversion type you are wanting to perform. Once complete, click the output field and the converted MAC address will be copied to your clipboard.