Couple of intresting links below -
1. Logstash - http://logstash.net/ - Powerfull log processor. Takes logs from many sources, applies many filters and provides output. One of many outputs can be ElasticSearch-cluster, with fancy webfrontend for searching, also many plugins exists (for amqp, greylog2, graphite, etc). This tool is similar to Splunk, maybe it's not cool as Splunk is - but for free (Splunk price is not for fainted of heart).
2. Varnish Book - "From creators of Varnish". :) PDF and epub will be soon.