Signup for a lot of newsletters? Well there is a way to individualise each newsletter just by adjusting your email address. Say your email is firstname.lastname@example.org and you fancy signing up for bt vault or another file back up service, you could just signup using email@example.com. Another example would be if you were signing up for web hosting you could use firstname.lastname@example.org.
What now? You could easily create a filter based on any of the above addresses and organise your inbox.