AniDB

anidbtool is a command-line application to hash files and add them to AniDB/edit their data. Can be used through "Send To" menu in the explorer interface as well as from the console.

Main features:
-Lovely command-line interface for command-line interface freaks.
-Strict compliance to AniDB short-term timeout rules. (I.e. you will not get banned suddenly because you've made too many requests in a short while. Well, you should not get.)
-Hash and file caches (no requests and rehashings for files you've added already).
-Auto-edit for files already in your mylist.
-Smoothly integrates into the Explorer through the Send To menu.
-Kind of optimized for multithreading (there's only so much you can do with AniDB timeouts though).
-Does not encrypt your password while sending it through the network, thus allowing every hacker to steal it.