Healthy service applications are very important to a SharePoint 2010 Farm. When SharePoint 2010 was new, there was a lot of attention paid to them. The shift from the Shared Service Providers of SharePoint 2007 and earlier to the new model for 2010 was significant, both understanding the underlying concepts and the effects the shift had on the platform.
Whether you are just creating your first SharePoint 2010 Farm, maintaining an existing Farm or refreshing your server application chops, I found a good series of articles from the past that can help you get up to speed
A good collection of short articles from Spence
I’ve been a big fan of Spencer Harbar’s blog going back most of 7 years to the Microsoft Content Management Server days. After having attended the Microsoft Certified Master course where Spence teaches a lot, I’ve given it even more attention.
I recommend that anyone responsible for setting up a reliable SharePoint 2010 Farm read the following articles to get up to speed or review Service Application concepts. They are all short, but very good references.