When you start an online business get a gmail account for your business. Google own so much on the internet now that it is easier to have a google email because then you can use it to log in to all the different services.

You will need a gmail account (or at least it makes signing up easier)

to start a blogger blog
to open a Youtube account
to open an adsense account (you definitely want to do that)
to use an adwords account (when you are ready to advertise)
to add your products to their merchant account
to run an analytics account

There are quite a few others that it is easier just to have one. Plus it is so much better than most other accounts as you will know when you experience it for yourself.

To open one visit

https://www.google.com/accounts/NewAccount