Here's my challenge, I want to do two linked menus for the archives. If you don't know what I mean, here's an example:

In Dropdown menu one, you select an archive type, such as Master Archives, Monthly, Catergory

In Dropdown menu two, the content will change based on the selection in one, so like if you chose Master archives in dropdown one, dropdown two would show "Full Archive List, Full Monthly, and Full Monthly drilldown" then if you chose monthly, it would show all the monthlies, and same for catergory.

Then, when you selected something in the second menu, it will take you to that.

Now, I have tried to figure out a way, but keep running into one problem: I would need MT to be able to do math to enumerate the arrays. So, does anyone have any other suggestions?

The dynamic menus will have to be done in Javascript.
There might be a way to use MT tags to populate the Javascript arrays for your SELECT menus. Otherwise, populating the arrays could be done with PHP.

Have you tried using associative arrays? Array indices in Javascript and PHP don't necessarily have to be numeric, you know.