From the webpage:
Solrmarc can index your marc records into apache solr. It also comes with an improved version of marc4j that improves handling of UTF-8 characters, is more forgiving of malformed marc data, and can recover from data errors gracefully. This indexer is used by blacklight (http://blacklight.rubyforge.org) and vufind (http://www.vufind.org/) but it can also be used as a standalone project.
Nice if short discussion of custom indexing with SolrMarc.