Logstash+Elasticsearch+Kibana
Flume+Elasticsearch+Kibana or Flume+HDFS+HIVE+PIG
Graylog2
Fluentd+MongoDB

scala+spark
http://alvinalexander.com/scala/analyzing-apache-access-logs-files-spark-scala
http://www.jdon.com/bigdata/analyzing-apache-access-logs-files-spark-scala.html
http://databricks.gitbooks.io/databricks-spark-reference-applications/content/logs_analyzer/chapter2/README.html

elasticsearch/logstash
https://www.elastic.co/about/press/elasticsearch-releases-logstash-1-4-makes-log-analysis-faster-simpler

http://drops.wooyun.org/tips/2821