When browsing a project, users are currently presented with a default set of filters on each of the project tabs. For example, on the Summary tab, there are Issues Due, Issues 30 Day Summary, Activity Stream, Issues Updated Recently, etc.; and on the Issues tab, there are Unresolved by Priority, Unresolved by Assignee, Status Summary, etc. These filters are the defaults, as programmed by Atlassian, and can't easily be changed.
I think it would be a very useful improvement to allow either the JIRA administrator or the individual project administrator to choose which filters to display and which filters to hide on each of the project panel tabs. They should be able to choose from a list of standard filters, but should also be able to easily create new filters to include (for example) custom fields. It should not require a programmer to do this.
Example A: the JIRA admin might configure the system so that on ALL projects, the Summary tab will display Issues Closed Recently instead of Issues Updated Recently.
Example B: on one particular project, the project admin might configure it so that the Issues tab will show Unresolved Issues by Type instead of Unresolved by Component, and Unresolved Issues by Severity (a custom field).