First site: Inboxdollars.com

This was the first PTR/PTC site that I joined. It offers multiple ways to make money, including paid e-mails, paid surveys, cash offers, cash shopping, and cash games. While I have not tried out ALL of the services, I can say for certain that this is a good site, as long as you watch some of the cash offers, but more on that later.
As far as basic info goes, this site has been up for a number of years, and is still going strong. There is a plentitude of payment proof (just google image search: "inboxdollars" "proof of payment"), of which this is a perfect example:
http://i627.photobucket.com/albums/tt354/Shadowsol93/Inboxdollarsproof-1.jpg. (NOTE: This proof is not personal proof, it's someone elses.)

There is a $5.00 sign-up bonus, and minimum payout is currently at $30.00. The payout method is a check mailed to you. The frequency of payments, according to the Inbox Dollars FAQ is
"Check payments are processed on a Net-30 payment schedule. For example, if you request payment any day in the month of January, your payment is processed on March 1st. If the first of the month falls on a weekend or national holiday, payments are processed on the next working business day. Checks are mailed through the U. S. Postal Service and should typically arrive within a few business days. Please allow up to two weeks for your check to arrive. Delivery time depends on many factors, including your geographic location, seasonal increases in mail volume, and totally dependent upon the U.S. Postal Service."
Once you successfully request payment for the first time, your account is automatically upgraded to Gold. There are some nice benefits, one of which is the ability to request payment weekly rather than monthly.

Now, on to the earning methods...
The simplest earning method is to just sign up, and wait for the paid e-mails to start coming in. Each e-mail is worth $0.02 and you can get anywhere from 5 - 20 e-mails a day (I know, big variation). These emails are safe enough, but you should keep up your guard about the sites that they link to. Most are harmless (as long as you don't click anything), but you never know.
Another method offered is paid surveys. While you will not qualify for all of them, they are (mostly) relatively short, and are worth $0.50 each. This is personally my preferred method for earning on this site.

A third method that you can use is to complete the Cash Offers that they provide. While this is definitely the quickest way to make money, you have to keep your guard up while checking out some of these links. The type of offer can vary from signing up with another paid survey site, to signing up for a free trial of something, to those adds that say that you're eligible for a million dollars. Also, rather than track the link themselves, Inbox Dollars sends the advertisers a message requesting confirmation that the offer was completed. While most of these offers do confirm with in a day or two, some may take up to 30 days to respond. I wouldn't recommend using this method as your primary money source on this site, but that's just me.

As for the Cash Games, I can't say much on this. It takes you to an affiliate site, which looks legit. You automatically sign up when you sign up for Inbox Dollars, but the account is unactivated, and no one will contact you if you don't click the Cash Games link. If you actually want to make money off of these games, you have to upgrade your account, and put money into it, either $10 or $20, which is matched by the site. I'm not too sure just how trustable this site is, but I can't check as it won't let me upgrade my account, due to he laws of the state that I live in (if that tells you anything.)

The final method is Cash Shopping. I've yet to try this method, but what I've been able to discern is that it works as a cash back program. You click the add, buy crap from the site, and earn xx% cash back. The most is 10%, while the least is 0.4%. Like I said, I haven't tried this, so I can't recommend it.
Anyways, I highly recommend this site. Just keep your wits about you, and you'll be making money in no time!

Referral Link: http://www.inboxdollars.com/?r=ref5767499