OK, as a long-time AAPL stockholder, which makes up the overwhelming majority of my holdings, here's what I think Apple should do with it:
1. Buy TiVo. It's super-cheap, and it can save the Apple TV. iTunes video store isn't working so well (see main page posting), with content providers like NBC balking, so integrating DVR functionality into the ATV will make it a must-have device. When the iTunes store first started offering video for sale, it was important for Apple to assuage the fears of the content providers by excluding DVR functionality. But in this new hostile environment, let people record their own content instead of buying it. They can of course keep the video store around for people who would like to buy content they don't have access to over the air/cable (or hate commercials), and perhaps keep the current TiVo/Amazon partnership for even more content (NBC). Think about how awesome it would be to have your Apple TiVo record shows for you and automatically transfer them into iTunes to put on your iPod. Apple and TiVo are a natural fit, with rabidly devoted fans, and they both have a commitment to gorgeous, intuitive interfaces. For a billion dollars, Apple could buy TiVo and retool the existing boxes and software. Instead of being a "hobby", the ATV could be Apple's iPod for the TV, as it was meant to be.
2. Pay a dividend. I know everyone (who isn't holding AAPL) thinks this is "greed" on the part of shareholders, but it's not. It will make Apple a genuine blue-chip, and attract many more investment dollars both from institutional investors who will have more incentive to hold Apple (as it is generating income even without selling the shares), as well as individual investors who will view the stock as less risky, as it will pay a guaranteed amount like a CD or other interest-bearing security. It will raise the share price dramatically, as well as the perceived value of the company and its stability.
I don't think the time is right for a buy-back. The shares are pretty highly-priced as it is, and are in no need of shoring up with a display of confidence like a buy back. If AAPL were to dip dramatically for some reason, a buy back would be appropriate.