At PCextreme. we use LogStash. in combination with ElasticSearch. to store most of our logs.
One thing we found is that although Grok has a lot of great build-in patterns, it sometimes is very hard to pare specific logs.
Since we are Open Source minded we thought it was a good idea to publish the LogStash Grok patterns we are using.
Most of them go with a bit of LogStash configuration as well to you can see how we use them.