I love my iPhone that I started using in July 2009. As a location photographer, having email and the web in my pocket is a big plus. However, checking email on an iPhone and a desktop meant weeding through as many as 50 spams per day on each device.
Enter Google Apps for domain names. I was able to configure my email with Google's gmail servers and still keep my gregbenson.com domain name in my email. I set up my iPhone, my desktop and laptop computers for IMAP email. Now I see virtually no spam and if I read an email on my desktop, my mobile phone shows it as already being read. Not having to scroll and delete interminable spam emails saves me time and aggravation.
To use Google Apps you can sign up here.
There are many productive apps for small businesses. Cloudwards has a list of 30.