DreamHost allows you to create wildcard addresses. These can be combined with Message Filters to easily sort your incoming email.
For example, start with an address such as firstname.lastname@example.org. Add to the user portion a + symbol and any custom keyword or text. Emails sent to email@example.com will be delivered normally to firstname.lastname@example.org.
You can also use these as "disposable" email addresses as well. For example, when you sign up for a specific service, you can give them your address as email@example.com. If you start getting junk from them, you can always set up a keyword filter to just delete any incoming message sent to that address. It's that simple.