This weekend, I installed RightFields, a plugin that allows you to customize the display of standard fields like Entry Body and to add custom fields. The plugin requires MT 3.2 and the BigPAPI plugin.
The plugin is very powerful with a ton of features that I am only beginning to explore. It is currently in beta and may contain bugs. To make full use of its features, you should also know how to add and modify MySQL tables in your MT database. So it's definitely not for every one. But if you're a power user, it may be just what you're looking for to greatly expand your use of MT.
RightFields is particularly helpful for non-standard blogs, when you're using MT almost like a database and putting unusual data in different fields. For instance, I use MT to produce links pages on my static website where I put the URL in the Entry Body field. Using RightFields, it is very easy to change the label that appears on the Create New Entry page, so that it says URL instead of Entry Body. You can make even further customizations than that. Plus you can add custom fields if you have more data than there are standard fields. I am not yet using this for the blog that manages my link pages.
The other feature that I am using is the Linked Entry. This is a special type of custom field that allows you to designate the entry as being linked to another entry, either in that blog or in another blog. I am using this here on the Tips blog. If you go to RSS feeds for tags, you'll see a section called "Related" and it says "This tip is built on the following tip(s)" and it lists another entry there. That is the linked entry. If you click through to using keywords and tags to help visitors find related content, you can see that it links back to the RSS feeds entry and to several other entries.
So this is a great way to show how some of your content is related to other content and direct visitors to that related content.
I am investigating a possible bug with this feature in which it appears to blank out a couple of the other entry fields (which I will be reporting to the developer once I have all the data), so you may want to hold off on implementing it if you don't have time to be a beta tester. Update: See bug report and patch to resolve it.
But it's worth it, in my opinion. And there's much more that RightFields can do.
Update: A release version, RightFields 1.02, is now available. Enjoy!