After reading an article in InfoWorld, I investigated this new (to me) service called Emailias.com. Try it for 60 days free. If it works as promised, I think $20/year would be a bargain. From their web site:
Unlimited number of unique disposable email aliases (Emailias) which you can provide with a single click for any web site.
Integrated Browser Button
Email Header Control Panel
Choose from multiple primary addresses where you can receive your email
Autorecall provides emailiases previously created for any web site
Reply Masking reroutes your replies back through emailias so that they can be made to appear to be coming from the appropriate address
Friend feature allows you to create a single use disposable address for friends when sending greeting cards or messages through other sites
AutoExpire allows you to automatically turn off an emailias after a certain number of days or number of emails
Organize Emailiases into folders
Disable Emailiases when contact is not needed such as in between ecommerce orders.
Clearly identify any parties who provide your address to others without your permission.
Easily control how you permanently "unsubscribe" from any mailing list or sender (and all of their "partners")
Does anyone have any experience with this service?