Sadly this is not nearly as effective as one might like, even with soundex hacks (or Levenshtein distance hacks). When I joined Google they had a class/project

Sadly this is not nearly as effective as one might like, even with soundex hacks (or Levenshtein distance hacks). When I joined Google they had a class/project for new hires that taught the map reduce system which was to process the complete works of Shakespeare (it is an easy corpus to get online) and come up with an index to extract interesting information or find specific quotes etc. It was a good way to develop an intuition for some of the challenges. Some things that bite you are of course spelling errors and OCR errors and sometimes formatting things (like where a line break ended up). There are strategies for overcoming those (some more effective than others) but as you dig into the problem you can develop a good feel for the complexity.