said by fegul :

It would certainly make you seem more influential, and yes businesses would probably pay more attention to you.

said by EUS :

Grand Poobah.
You should probably use President & CEO on your card.
I would not use President/Consultant, as that looks a bit strange.
If people don't know what you do when you give them your business card, there's a problem with either your business name, or description of work that should be on the card already.
For example:

ABC, Inc.
John Doe, President/Consultant

ABC, Inc.
Computing consultants you can trust.
John Doe, President & CEO

said by Quantum :

CEO is a prestigious title which is reserved for the head honcho of a corporation (large enterprise). The CEO is the boss of all other CO, such as CIO, COO, CFO and so on.

Unless you have another CO that reports to you, I do not think that CEO is an appropriate title for a small business owner [ 500 employees max].

The title of president, shows that you rule the company and that you are involved in the day to day activities, you do not delegate everything.

Title of founder shows that you have created this company and that you are an entrepreneur.

In your case, it might be good to have president & founder as your title.

On a side note, I remember one day talking to somebody who told me that she was the CEO of a company and she was going on and on about her company and herself. I finally decided to ask her about the size of her organization, and what they do, since clearly it was a no name.

Turns out it was a group of about 6~7 people who were designing web pages under a common name and since they all started the 'company', they all gave themselves title of CEO.

I couldn't stop laughing!

Point of the story, giving yourself a title of CEO will not make your work or your worth any more that what it is, in reality it might make you look like a wanna be, instead.