MortButtons is freeware, i.e., you can use it without paying. But if you like it, I'd be grateful for a small (or big ;)) donation:

Despite the name, MortButtons is NOT a tool to assign applications to buttons, like BtnPlus, VITO ButtonMapper, PowerButton, and similar tools.

Instead, MortButtons is a menu system or launcher tool.
It's not meant to be a replacement for the Start menu of Windows, but rather as a "quick start" for the most important applications, documents, and functions.

What makes MortButtons special is:

• There are 5 main menus (and as many sub menus as you like)
• Each of these menus can be used with just one button, if it's assigned to an application button. Each time the button is pressed, the next entry is highlighted. After a selectable timespan, the highlightet entry will be started. (Of course, tapping or DPad+"Fire" works, too)
• Extensive possibilities for skins. Just take a glance at the existing ones.
• The menu can occupy either only the rectangle required for the entries or show an own background in the unused area
• The Today theme can be used as menu background
• You can choose between big or small icons. Or automatically: If the entries don't fit on a screen with big icons, the small ones are used.
• Possible entries include all start menu entires, (almost) all files of the entire file system, menu entries from the "New" menu (req. at least WM2003), and some internal functions (e.g. rotation, activation of existing windows, sub menus, etc.)
• Screen orientation can be changed with application launch (e.g. Internet Explorer in landscape)
• The task list is a menu, too. It can be activated either directly or as sub menu. MortButtons allows Minimize, Close, Close all, and Close all but current in both the task list and any user defined menu.

A manual, alternative Skins, and some other informations can be found here.