Lucene offers powerful features through a simple API

• over 200MB/hour on Pentium II/266
  
• incremental indexing as fast as batch indexing
• small RAM requirements -- only 1MB heap
• index size roughly 30% the size of text indexed

• ranked searching -- best results returned first
• boolean and phrase queries
• fielded searching (e.g., title, author, contents)
• date-range searching
• multiple-index searching with merged results

• incorporate new document types
• localize for new languages (already handles most European languages)
• develop new user interfaces

• 100%-pure Java