AdSense:

Contextual Ads
$100 Minimum Payment
Check and EFT
*Approval needed.

Undoubtably the "king of the jungle" at present, it seems to be the favourite starter CPC network. They have strict policies, but plenty of resources for Q&A throughout the site. Many say they have been "banned for no reason", but there is always a reason. The truth is, if you do the right thing (and they give you plenty of information in simple terms, to prevent you making a mistake), you will be happy with the outcome. The ads are very targetted worldwide, so if you have visitors from another country, the ads will reflect their IP and even show them in the language of the country if it isn't an English speaking country.

Clicksor:

Contextual Ads
$50 Minimum Payment
PayPal and Check
*Approval needed.

I haven't personally used this network, but I see reports of non targetted ads. They have a lower payout threshhold than google, so should be worth a try whether you have a paypal account or not.

Bidvertiser:

$10 Minimum Payment ($50 for check)
PayPal and Check
*Approval needed.

I have had varying reviews about this company. I might need to give them a try for a more accurate review. I can't say I have seen a site with bidvertiser ads, so I a not sure if they are targetted or not unless I try them.

Quoted from their site:

"Make money from your website or blog - get paid for every click!

Join BidVertiser now and we will turn your advertising space into cash! Simply display the BidVertiser text ads on your website and let advertisers bid against each other! We will always display the highest bidders to maximize your revenue so you will make more money!"

AdEngage:

Sell ads on your site
You get 75% of the ad revenue
PayPal and Check
  More information coming.

Yahoo Publisher Network (YPN):

Contextual Ads
*Beta Program (USA only)

This network appears to be well recommended by US publishers. There is no ETA as to making it available to more countries at this stage. The ads I have seen are not targetted to my area. It appears they have "warning" system in place if you step over the line as far as their TOS goes.:

"If a compliance issue is detected on one of your URLs, you will be notified via email and through an alert in your secure account interface. These will direct you to your new Compliance Manager control panel. The Compliance Manager will inform you of what the issue is so that you have the opportunity to fix it. Once you’ve addressed the issue, you can then go back to the Compliance Manager to submit the remedied URL. We’ll get back to you with a status report, usually within seven business days."