To market your local business online, there are a couple of steps that if taken will dramatically increase your local online visibility and drive your business through the roof.

Optimize Your Website
First things first, your website must be search engine optimized for local searches.

This means for each page on your website you must have  your business address and contact information visible.
You should also write articles and or blog posts with your business specialty in mind and with the location in the title. For instance: Marketing Your Business In Mississauga or Custom Software Development in Mississauga. And do this often.
You website should have a page dedicated just for just contact information, where you can put your contact form, address and a Google Map.
Create a KML file which displays geographical data for Google Maps and Google Earth ( use this online utility to create a file)
Make a YouTube video of your services and make sure that your locacation is in the title and description of the video.

Claim Your Business On Search Engines
It really amazed me when I was looking for Sushi how many local Sushi restaurants did not pay enough attention to there local business listing on Google.

Go to Google, Yahoo and Bing and claim your local business page and upload photos and website details. For instance you can go here to register you local business on Google.
Get friends and customers to write reviews with there Google accounts for your local business. When I was looking for a Sushi restaurant all I did was [...]