I figured since so many people on here use Craigslist for equipment, this might help. I've been doing this for a while now.
If you're searching for something specific, you can use Google alerts to tell you when a new post hits Craigslist. Google will send you an email as soon as something new matches your Craigslist search. The text-only email will contain the Craigslist posting title as well as the first few lines of the post and a direct link to it, so it works well with cell phones.
Prepare your google query as follows:
<search string> site:<city>.craigslist.org
So, if I want to be alerted when a 7 string Ibanez guitar appears in austin, I would search for:
7 string ibanez site:austin.craigslist.org
Click search. Now click on the News link at the top. Then, click on News Alerts on the left toolbar.
Make sure the "Search terms" field has your search string in it. Change the Type field to Web.
Change the How Often field to As it happens.
Type in your email and submit the information. You will get a confirmation email shortly.
You can use this technique for many other sites, just be aware that you're going to get an email every time there is a new match in the google query.
If you aren't in the US, you'll have to use whatever domain is appropriate instead of <cityname>.craigslist.org
, like <cityname>.en.craigslist.ca
If you want it to send you a text message instead, you can use the following email format, depending on your provider. If you want to get updates on your phone, this would be much faster than email since email generally has to be refreshed at certain increments, where texting is more or less instant. However, be aware that text messages are (generally) 160 characters, so it's going to truncate a bunch of the email and you will have to get to a computer to be able to read the whole post OR you can set up a second alert sent to an email address on your phone, so that when you get the text, you can manually refresh your email to read the whole thing.
Here are the formats for some different providers. If yours isn't on here, just search for it. They all have this capability.
Alltel email@example.com firstname.lastname@example.org
ATT email@example.com firstname.lastname@example.org
Cingular email@example.com firstname.lastname@example.org
Metro PCS mobilenumber@mymetroPCS.com 4155551212@mymetroPCS.com
Nextel email@example.com firstname.lastname@example.org
Sprint email@example.com firstname.lastname@example.org
T-Mobile email@example.com firstname.lastname@example.org
Verizon email@example.com firstname.lastname@example.org