Mail

Referrals - the easiest way to expand your business. Use the invite system to encourage your users to spread the word about your business and track who are your biggest fans...and reward them for referring you.

It's especially handy for blogging sites when you are on the road...you can use your phone to email content to your website and have it instantly published! You don't even need a SmartPhone...just any phone that you can email from (which is most these days).