Today I got asked how to modify the search box on a MOSS site so that it displayed "People" by default in stead of "All Sites". The customer already figured out a way to do this with code, but they weren't 100% sure about it. I had to search for this myself too, cause to be honest, I hadn't done this before, even though I'm already working with SharePoint for almost 3 years now... That's why I'm making this short post, so that all the other people who are trying to do this, know how easy it really is.
To modify the default scope, go to your home page and navigate to "Site Actions” --> “Site Settings” --> “Modify All Site Settings". On this page, pick "Search scopes" under the Site Collection Administration. Here you'll see some different "Display groups", one of them is the "Search Dropdown", which is the search box you see on your SharePoint site. If you click on the "Search Dropdown" link, you'll be taken to a page with some settings for this group and the bottom one is where you set your default scope. So modify this to whatever you want, click OK and you're done!