I use addy.io to create aliases for different things, and then set up filters in Thunderbird to mark them as they come in so, for example, if I make an account at xyz.com and then I get a bunch of unrelated spam marked as coming from xyz.com, then I know they've been selling my info.
I probably have about a dozen or so aliases currently, but they're pretty loosely organized.
I probably will end up with tons eventually, I haven't been doing it for too long and I don't sign up for many things lol