We got a balance/run bike for our three-year-old and he has loved it. I looked at several different ones and finally settled on a Kazam bike. I thought the Skuut and a couple other wooden models (perhaps the Strider, I can't remember) were definitely cuter (one of them even had a handle in the body, which I thought would be so handy for hauling it around and loading it into the car) but I was concerned about durability and steerability. I also didn't want to spend more than $100, and a couple models I looked at were really spendy.
I think the Kazam deserves consideration. We've been really happy with it. The Kazam is metal and comes in pink or blue. It doesn't have that uber-natural, Waldorf-wood look, but I think it is dang cute. What sold me, though, was the little footrest. It can be used like a scooter or the child can sit and use it as a run bike and scoot along, and when the child is confident enough, s/he can coast down hills and has a place to but his/her feet! It reminds me of a tiny Vespa.
I bought the Kazam as a fun outdoor toy in itself, not necessarily as a major training aid for learning to operate a two-wheeled bicycle, and my child is still just enjoying this run bike, so I can't say if it makes the transition to a regular bicycle easier or faster. But we really like it. The only downside is that it is small and lightweight (advantages, most of the time) but that means it cannot hold heavier children. We had to make sure our seven-year-old knew he was not to play with his little brother's run bike--but he's hardly tempted. I wish we'd had one of these when he was little. Our best friends have a two-year-old and they are looking forward to the hand-me-down Kazam in another year.
I think I compared models at www.runbikes.com, which I found through Google.
Happy birthday!