Registration SuggestionsFollow

I've noticed a lot of "gil ad users" recently, and I have a feeling that some are bots registering many accounts. Other web sites use random number/letter generators in their registration forms (a user must enter whatever is shown in an image in order to register) to reduce/prevent bots, so perhaps something similar can be implemented here. Another option is to make users agree to some sort of Terms of Service when they register. The second idea can also be used to reduce trolls/flooders/etc...