Salesforce Reports have the ability to create a custom bucket. The Bucket is essentially a custom formula that groups fields dynamically within a report. Previous to the bucket feature, an administrator was needed to create a custom formula field to do the grouping. The bucket field is much more flexible as it can be used by any user that has access to edit reports, can be changed on the fly, and doesn't require the consumption of a custom formula field.
As a simple example, I created a Bucket Field that groups Opportunities by Amount:
And you can see the results here:
I wanted to call this feature out not as a tool that Admins can use but rather as a tool Admins can train their end users on in order to avoid custom development (i.e. Formula fields) as they aren't needed for reporting purposes. The trick is, if you can empower your users through training on bucket fields you get to avoid creating custom formula fields for reporting purposes and your users have a better user experience with Salesforce.
Now for the admin stuff... You can use a Custom Bucket Field in a Report Summary Formula! Super Cool!
Training to get your users started: