bike basket/bag/rack?

Since this winter I've been the proud owner of a used Specialized Crossroads mountain bike. I like it a lot, but I realize that I would like it more and use it more if I had some kind of carrying devise attached to the bike so that I don't have to attach as many bags and backpacks to myself while I ride it.

The bike is basically this, but older: http://images.google.com/imgres?imgurl=http://www.mikesbike.com/newbikes/05ExpeditionSport_Silver_l.jpg&imgrefurl=http://www.mikesbike.com/pages/exped.htm&h=324&w=432&sz=39&hl=en&start=6&tbnid=JYIvCXjVytK5jM:&tbnh=95&tbnw=126&prev=/images%3Fq%3Dspecialized%2Bcrossroads%2Bbike%26gbv%3D2%26hl%3Den%26sa%3DG

Does anyone have any recommendations for baskets or racks or things that I can easily buy and install on my bike? (I have basic household tools and am comfortable using them, but I don't own any special bicycle tools.)