One of the most useful 'business' tools I've added to my little arsenal (telephone, digital camera, MacBook, car) is actually my iPod Touch.
Originally I used this handy little thing mainly for listening to music, podcasts and audio books, as well as playing games occasionally. (*cough* er.. honestly, just every now and then, the odd game of Solitaire.)
But now I've discovered what a powerful little tool it is for helping me get this whole thing off the ground. It is so utterly portable - it weighs even less than an iPhone - that I can take it with me all round the house and garden, bringing the concept of "working from home" smack bang into the 21st Century for me.
I use it a lot, for example, for Twitter. I have three Twitter streams for the various different elements of my life, and the App I use (Echofon for iPhone, if you're interested) and it allows me to tweet even more easily than I can from my MacBook - for example, I can instantly switch between Twitter identities without having so sign out and sign in again, and I can re-tweet with a comment, which is harder to do via my web browser.
I can also re-tweet myself, which saves a great deal of time when I am seeking to get my message across to different time-zones.
My iPod Touch, this natty little gizmo, means I can manage Twitter, LinkedIn and Facebook (though the app I use is not entirely satisfactory - I'd love to hear your recommendations of other apps) from anywhere in the house .. or garden. I can Tweet from the hen house. I can connect with people on LinkedIn whilst 'chained' to the kitchen sink. I can fart about on Facebook whilst looking in the bathroom mirror, and polish up my Eventbrite page whilst dusting my bookshelves. It's fabulous.