Resource Button Maker →
From the addons page: Create your own unique web buttons. 1. Add your own button graphic - background and hover image - to the resources area. 2. Style your button - make it hover… and jump a little. DiskImage includes: The ButtonMakerStack - a link helper stack - a demo example to give you an easy start + bonus 960-3 column stack (fixed 960 pixels width).
From the addons page: ImageRoundr gives your images round corners - no extra work is needed on your end. We’ve also created ImageRoundr so you can place other stacks in it - if the stack has images they will be rounded.
Power Button →
Power Button creates button groups with nice gradients and effects like drop shadows and rounded corners. From the demo page: Power button is designed to create single or multiple bar type buttons Should you choose to have rounded corners on the button arrangement, you can be sure they will still be there in Internet Explorer also.