From Fitz ...

... the most interesting new thing I saw all day - Ontolica ... created a shrink-wrapped add-on for SPS and WSS that rips out our default search UI and replaces it with something much, much nicer, much more powerful, and much more flexible. If you were thinking about replacing or supplmenting our native search technology with someone else's, I'd encourage you to look at this first. Their enhanced UI will show you just how powerful SPS search engine really is.

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Also check out Longitude Search for SharePoint Portal .