Quite often the filtering requirements of a client exceed the standard filters.  It would be an excellent option to expand upon the list of available filters, adding our own custom elements (and logic via an event handler), and relative to the type of column.  For example, we have a client that wants a grid of all "to-do tasks" coming due, but their list can extend years in advance.  Some users want it to look ahead 7 days (which you have), others want it to look ahead 1 month (which you don't).  Others want a combination of these, 7 days for one type of task, 1 month for other types.  If we could add our OWN items to the filters, this would solve the problem and create amazing flexibility in this tool.