Rafał Kuć has a multi-part series on Solr and its autocomplete feature:
Solr and autocomplete (part 1)
Solr and autocomplete (part 2)
Solr and autocomplete (part 3)
Part 4 to appear.
Autocompletion is common enough that I suspect it has or will shortly become a user expectation for search interfaces.
Customizing the dictionary (in part 3) will help you provide better guidance to users than seen in general search engines.