I was half expecting to write a very long, detailed review of the Keyword Manager for iPhoto. However, I will not. I will just say that if you are the type of person that is willing to invest in their personal data's future - and the ability to find it quickly and easily, the Keyword Manager for iPhoto is your key.
Personally, I recommend paying full price for the Keyword Manager. It is completely worth it, and the support is top notch. There are ways to save money (via MacZot today only, and using Coupon Codes that you can find just about everywhere), but I suggest strongly that you purchase a copy at full price.
John Gruber said it best "Aim for high quality and set your price accordingly.". The developers of Keyword Manager have done just that, and while they are trying to get their name out there with these promotions - I still believe that this is one plugin that is worth more than it's price tag.
[tags]iphoto, apple, macintosh, keywords, tagging, bullstorm, keyword manager, john gruber, daringfireball, maczot[/tags]