My absolute favorite keyboard ever is the one I currently have - a Logitech Solar K750.
I like it because it's has laptop style keys - but are more substantial than usual laptop keys.
It is a full keyboard with number pad and all the 'home/delete/pg up down' etc keys in the right place (you'd be amazed how many of the laptop style keyboards mess around with positioning of these keys).
It's an absolute joy to type on, so much so that I bought an extra one for my office computer and even bought a mac version for my hackintosh.
Bonus is that you don't need batteries for it!
They're pretty spendy $65 or so), but they go on sale quite a lot - Best Buy had them for $39 last week for example.
The only thing that could improve it in my mind was if it came with 10 or so programmable keys so I could program macro shortcuts for Visual Studio and Photoshop etc. Until that day, I use one of these instead and that works out really well.
You'd be amazed how much more productive you can be assigning a single key to outlining - collapse and outlining - expand for Visual Studio as an example. Sounds silly, but is true.