I encourage you to continue in your efforts, and I will add some suggestions on how you might proceed which will get you further along.

First, in order to scale, it will have to be able to run on 'n' servers. So look at ways of breaking up your index across multiple machines and operating on the index in parallel.

Second, crawling can often be a bigger challenge than providing search results, so work on building a system that can crawl a bunch of different web sites. Folks like Octopart have shown that topical search engines are really useful. So consider putting together a billion document index of say "news sources".

In the 'everything that is old is new again' theme, consider building simply a 'blog search engine' which is one that focuses on various blog content. The old Technorati did that and later was subsumed and its become harder for blog writers to rank in Google's results, so perhaps there is an opening for a place to search about who is talking about 'x' for some X.

I happen to know you can run a pretty decent crawler and indexer for about $2M a year :-) so consider targeting your donation rate to hit about $150,000 a month.