For many businesses the contact page is the money page. So you should make sure it does it's job.http://ow.ly/Pd41i
Nicole Leedham explains the key points to creating a contact page that works. Get these right so you don't put potential customers off.
Some bonus points from my technical SEO viewpoint:
If you have walk in visitors then add a map.
Make sure you are very consistent with your business Name, Address and Phone number (NAP) in all places you use it online. Google uses it as a way to determine that it is really you.
Use branded email addresses and avoid free ones like @gmail. You want to look professional.
For local businesses a local number can add a level of trust while national businesses may find free call numbers are the best.
If you are active in social media then why not push it here. They want to chat.
Try and include proof that you are a legitimate business. e.g in Australia you could show your Australian Business Number (ABN)
You can make phone numbers into links so mobile users can directly call:
<a href="tel:0123456789">01 2345 6789</a>
Give them a nice experience after the hit that submit button. Make sure it's clear to them that it was sent, say thank you, and for a gold star suggest they do more, like visit your Facebook page.
For the advanced you can semantically mark up things like your phone number, address and opening hours to help search engines fully understand what you are telling them about your business. Here's a starting point for a local business:http://schema.org/LocalBusiness
On a related note, a well coded form will let the browsers auto fill form fields. When that fails I personally get annoyed. Even worse are forms that don't handle errors in a user friendly way. e.g. having to scroll to find a cryptic error message.
So, polish up your contact pages.