add a Facebook share button!
Before you do this though, you should make sure that you have done a 
few things first.  Give your listing a good title.  One of the worst things
 you can do is give a vague description.  Once you’ve come up with
 a title, take a moment to do a little homework.  Think about the 
things that someone reading your listing might call of email you about. 
 If you put these details in the listing, you’ll have less questions to
 answer and more serious inquiries to work with.  The greatest 
thing you can add to your listing- a good photo!  There are
 numerous ways to do this, the easiest is right through craigslist. 
 The next is to add an image using an online photo sharing site
 like Photobucket, which will generate the code you need to 
copy paste automatically after you’ve uploaded your image.
Now comes the best part- adding the Facebook share button. 
 You can make your own, or use this one…
To use this idea, you need to create your listing first.  Once it’s done,
 get the link for the page.  You’ll need this to make the button work.
  Go back and edit your page, adding the button code at the
 bottom, and including your craigslist hyperlink.  It should look 
something like this:
<a href="">
<img src="
Light Blue: This is the url link which allows you to post on your Facebook page
Pink: This is your craigslist listing url
Orange: This is the image code you can cut and paste from your Photobucket 
account, or other uploaded source.  Just change the url to your image
(shown in dark orange) url.
I hope this helps you get more attention for your craigslist page!