Start here:Arduino Home Page
The Arduino Playground link there is pretty fun to check out too.
A couple basic sources:Spark Fun Arduino stuff
(which seems to me to be less of an industry but more the brainchild entrepreneurial success of a splendidly geeky girl from MIT - some cool stuff there to be sure)
There are a ton of sources for Arduino on the net though, so I encourage you to google before buying.
You can even try eBay, where an Arduino can be had for around $10 I think.
The best "tutorial" projects resource I've found is in PDF book form which is here (click)
And the code used in that book is here (click)
good. Check it out.
BTW, it came from this place (click)
(under "arduino compatible projects" and "starter kits")
The "starter kit" they sell might be useful too but it's pretty much just standard electronics/robotics components which you may already have. Seems kind of pricey to me, but it's all there to follow along with the projects in the book - maybe worth it for the convenience?
They provide a nice pictorial list of what is in the kit so you can look that over to see what you need to follow along with the book.
Well that ought to get you going. My recommendations are just one guy's perspective. There are a lot of other resources out there too.
p.s. The standard, typical place folks start with Arduino isn't quite a "robot", but are a progression of projects which show you how to hook things up and code for a microcontroller. Everything you learn by going through those projects is applicable to whatever robot you want to build. I mention this because if you're chomping at the bit to get a robot rolling around your living room, this will seem like a step backward. It's not. It's simply the first steps toward wrapping your head around a robot controller. You can make a robot without a microcontroller (and I think the $50 robot from this site starts with something like that IIRC). But to me that is kind of
a tangent since, at least for what I want to do with robotics and automation, the microcontroller is the core around which I wrap the rest of what I like to do with it. Anyways, trying to remain in step with the idea of keeping things simple and linear, I believe that starting by learning how to use the microcontroller correctly is a good way to go. Making a robot using discrete components (i.e. no microcontroller) seems to me like an interesting project for later exploration - if there is interest and time to fiddle with it.
So in summary:
Look at some sources and order up an Arduino board.
Any time between this second and retirement, feel free to browse the Arduino home page linked above. Lots of useful info there to edify your inner geek.
Download and read through the tutorial manual linked above. Maybe buy the components you need to get through the first few (or all) of the projects in the book from the source of your choice.
Work through the tutorial projects and maybe some others (Adafruit has some good tutorials too - here (click)
If you're really jazzed up about it, the tutorials will probably only take a week or two to rip through. Try to make sure you have a solid understanding of every little tidbit though, since most everything after this will just build on it.
After that, you should have a pretty good idea where to turn next, and you'll have some micro kung-fu under your belt to work with.