Actually I am just getting started (after too long) using Yahoo's service which provides 500 disposable emails per account.
For those who don't know it works like this ...
You have you main account id which provides you emails address.
Withing the options section there is "Address Guard" in which you register a different id (say eg. nospam .... but that's bound to be gone!). Then you can set up up to 500 email addresses in the format [email protected]
where xxx is a chosen address for the service you are signing up for. For example if you were singing up to DC for newsletters you might choose [email protected]
All of these throwaway address you create are automatically delivered at your main address and can be filtered like ordinary mail if you want. You can even post using the dummy address.
Now you sign up with that address to DC only. If spam starts to arrive on that address you know where the address originated from and you can simply delete the dummy address. It doesn't affect any of your other subscriptions and because the email address doesn't contain any details of your main account name it can't be used to spam you mail inbox.
Works great - just wish I had started using it a while ago.