I'm a believer that you are more important than technology when it comes to having a successful business. Sure, technology is great, but it can also be a huge distraction that can take you away from your business. Rarely do you need the "latest and greatest" to make money.
Here are the tools I use most often...
My main computer is an iMac with a 20" screen, which is plenty large for what I need. My previous iMac had a 24" screen and using it was like sitting on the front row of a movie theater, so I decided to keep things small for this one.
I replace my main computer every two years, not because of improved technology, but because I make a living from ideas that are stored on my computer, I work my computers hard, and I want one that won't fail on me.
I've been using the same keyboard for 10+ years. It's loud, full of dirt, and it says "Macally" at the top left. It looks like it was made for one of those candy-colored iMacs, which is, I think, why I purchased it.
I use a Kensington Expert Mouse (which is really a trackball).
I use a Samsung Chromebook for writing, not because it's a great computer, but because it has less destractions than other computers I own.
To talk to the Big Boss, I use Skype.
For blogs, I use TypePad.
For email, I use Mailplane.
For password management, I use 1Password.
For task management, I use Things.
I use Arq for backing things up.
Pair is my main webhost.
I use Elance to find new people.
I have a Vonage phone that isn't plugged in.
I have a mail drop at The UPS Store.