Customizing Search Engines and Searching State Libraries

For one of my upcoming columns in Online, I compared the various custom search engines and other tools for building a topical search engine from a subset of a major search engine's database. Tools like Gigablast Custom Topic Search, Google Custom Search Engine, Live Search Macros, Swickis, Rollyo, and Yahoo! Search Builder. I compared a number of features (including the maximum number of sites, whether they support subdirectories, and if they have usage statistics). This information can now be seen on my new Customize Your Own Search Engine page.

In the process, I created a demonstration search engine with each tool. My project was to try to cover the Web sites of the 50 U.S. state libraries. See my new State Libraries: Custom Search Options Compared page to try them out. I plan on fleshing out both pages with more details. In the meantime, anybody know what the maximum number of sites supported in Google's Custom Search Engine is?