Currently, I use a Microsoft Comfort Curve Keyboard 2000. It's an ergonomic keyboard with a soft curve laterally, and no vertical curve (it lays flat). It's a wicked keyboard if your shoulder width is not so wide, because it has only that slight curve, rather than the dramatic curve of other ergonomic keyboards. It also has a light but distinctive touch, so it's easy to press the key down, but not so easy that you would accidentally "smoosh" a key down by accident. The key's travel — how far it travels from the start of pressing a key to bottoming out — is also quite short, so there's less finger motion required to type.
Unfortunately, both of those keyboards, at least when used on a Mac, optionally suggests that you install the Microsoft IntelliType software. The IntelliType software has been known to apparently cause a lot of kernel panics for on Mac OS X — on the order of once or twice a day even, when under heavy typing load. If you use Windows, then this is not an issue (I've used both of those keyboards under Windows XP and Windows 7, and they work well). If you use a Mac, you may find my previous post on the issue useful.
The SideWinder X8 has 5 buttons (including the scrollwheel button). The scrollwheel has tilt function to scroll horizontally. It has three resolution settings for different speed of mouse cursor travel. It's rechargeable using AA rechargeable batteries, but it has a "base station" that it can recharge from so the batteries stay in the mouse. The connection with the base station is via a magnetically attached wire that can be unspooled so that the mouse can be used as though it's a wired mouse! The base station plugs into a USB port to draw power and to relay mouse instructions, so the computer doesn't need special set up. Having said that, you'll want Microsoft's IntelliPoint software installed or else all those buttons will be next to useless.
The X8 is the most comfortable pointing device I've used since the Kensington TurboBall Trackball I had long ago. Unfortunately, trackballs are out of fashion nowadays, and so good ones are hard to find, especially given that I want one that fits my hand well.