These work on all browsers (ok 6+ ones!). However, IE6 had some padding issues with #5, but that's IE6 for you! Also some of the roll-over/hovers don't work in IE6.
I've used a combination of hovers on the examples, so please look at the css (in this file) to see what I've done. Because of the way the roll-over/hovers are done in the css, you can get two states of roll-over/hover if you move the mouse slowly, but do it quick and it's pretty smooth!
Simple two colour buttons (Border on 'a' with padding on 'li')
Roll-over buttons (Border and padding on 'a' with padding 'li')
Same as #2 but vertical
Triple Borders! (Border and on padding on both 'a' and 'li')
In a block of text. You need big line-height to use this!
Floating as 'fake' buttons (Using only borders on a 'span' and 'a')