Fiverr can be a great place to find traffic providers that are in different niche markets and some that have unique sources of traffic that a larger company may not have the time to focus on, as well as a great place for those selling traffic to make their first sales. They have a review system which helps to weed out bad providers and it is wise to avoid listings with previous mediocre or poor reviews, and there are also a large number of people re-selling traffic bought from a wholesaler on Fiverr, and with that in mind you will want to look for sellers that give a good background to their traffic source and who appear to be the actual owners of the traffic source.
Horizon offers guaranteed website traffic, e-mail marketing, banner advertising and hosted services. Their website traffic can be purchased as country-specific, specific to a niche category or a combination of both, as well as e-mail lists that they can also send the mail for if you do not have your own servers.
Propeller Ads offers a range of traffic sources including pop-under, interstitial, banner ads and push notifications.
For those looking to monetize bulk redirect traffic, Propeller Ads offers a direct link that can act as a catch-all to monetize unused traffic from any of your domains at once.
Semrush is a powerful and easy to use SEO, content marketing, competitor research, PPC and social media marketing from just one platform. With their free account you can do a limited number of keyword lookups and other site analytics per day to meet basic keyword research needs.
Top Of The Results provides SEO/CTR traffic that will come from searches based on a keyword you select to improve the click-through ratio and on-page time for those keywords, and includes features such as scrolling and fine-tuned control of traffic behavior.
Udimi is the world's largest solo ad marketplace, which offers a place for sellers to post their serviices and for buyers to purchase advertising, which is all handled through a secure escrow through Udimi. Udimi also offers a nice affiliate interface and resources for those wishing to promote it.