When building WordPress themes for clients I often include custom admin options which help make the running of the website a lot easier for them. Things like custom images with captions, featured images, product and service call-outs, shortcodes for styling and many more custom integration options.
I have always hand-coded these lovely little options until recently when a friend and colleague of mine introduced me to the Advanced Custom Fields plugin. What ACF does is help you create a load of custom field options for use within the admin area of WordPress, you then simply call the correct custom field in your theme where you want those options to show up. Basically it's the same as hand-coding it all in but super-super quick and much easier to manage.
My initial concern was that I would be adding a plugin to the build, something that I like to keep to a minimum with my WordPress builds, but what this lovely little plugin lets you do is export all of your custom fields, that you have created with it, as php and then simply add that code into your functions.php file as normal. So you end up with the same result as hand-coding but it is easier to set up and manage during development. If you use WordPress' custom fields in your builds then I really think you should at least check it out.
You can get the stable release or the nightly build. More details are available on the ACF website.