Below are vendors that we have personally used and recommend:

DNS Services:

If you have a high volume website that produces substantial revenue for your organization, we urge you to consider using a third party DNS rather than using the default DNS services of your ISP (see our article on managing your own DNS). By doing so, you remove a critical single point of failure.

• DNS Made Easy  - DNS Made Easy offers managed DNS services at a fraction of the cost of its two main competitors. They use redundant DNS servers located worldwide that allows Internet traffic to take the shortest, most efficient path. Additional services offered are DNS Failover, System Monitoring and Secondary Email Backup.
  

Domain Registration:

Your domain names are a long term asset - think of it as virtual real estate. The annual registration fee is small, so don't just go on price.

• eNom - We like eNom for its businesslike interface, its customer support and its security.  They are one of the largest domain registrars in the world and are at no risk for going out of business.
  
  
• Moniker - Moniker is the premier domain registrar for corporate businesses. If your organization has its own marketing department and is concerned about branding issues, then Moniker is probably the way to go.
  

Email Marketing:

Building a mailing list to remain in contact with your customers is essential for long term growth. We recommend that you use a third party service to avoid spam complaint issues and to insure deliverability of your messages and newsletters.

• AWeber Communications -  By working with the major ISP's and adhering to a zero tolerance anti-spam policy, AWeber has far and away the best delivery percentage for email communications.
  

Hosting:

• HostGator - HostGator has excellent prices and terrific service. They offer hosting for both Linux and Windows servers. We find their offerings and options complete and up-to-date. All of their shared plans include a 99.9% uptime guarantee, 24/7 support and a 45-day money back guarantee.

• Liquid Web - If you have a high volume website and require industrial strength web hosting, we wholeheartedly recommend Liquid Web. They own their own datacenters staffed with their own engineers on-site. They promise 100% uptime with 24x7x365 support with access to level 3 engineers in seconds.

• WebHost4Life - If you require an advanced Microsoft platform for your web hosting, we have found WebHost4Life to have the most complete and up-to-date Microsoft offerings from ASP.net to SQL Server to AJAX.