Rumor has it that the next version of Microsoft Dynamics CRM will include significant enhancements to navigation. This functionality should be included in the version scheduled to be released in early 2010.

The idea seems to be to bring the navigation for CRM in line with the "Ribbon" (also known as the "Fluent UI") that appears in the Office 2007 products suite.
This new command bar replaces the CRM 4.0 "tool bars" at the top of each page, and is context sensitive.

In addition, the command bar is fully customizable and you can add your own buttons - as many as you would like.

Here's a sneak peak at the new CRM ribbon-style command bar:

Another cool feature appearing on the ribbon is the "Add to Marketing List" command, which appears to indicate that you will be able to add any entity (including custom entities) to a marketing list. This is a nice productivity enhancer.