As others have mentioned, nginx + one of the redis (or lua-redis) modules does this very well without the complexity of syslog in the middle. We load many millions of values a day via httpredis2. It's been rock solid.

http://wiki.nginx.org/HttpRedis2Module

We log the same requests to a file in a custom log format that gets batched to s3 and then Cassandra and EMR/Hive. Makes a great platform for realtime + historical analytics.