The above diagram, shows a Hadoop Ecosystem with the different features/tools used as a part of the Hadoop Implementation. (Open Source Projects) :
Eclipse is a popular IDE donated by IBM to the open source community.
Lucene is a text search engine library written in Java.
HBase is the Hadoop database.
Hive provides data warehousing tools to extract, transform and load data, and query this data stored in Hadoop files.
Pig is a platform for analyzing large data sets. It is a high level language for expressing data analysis.
Jaql, or jackal, is a query language for JavaScript open notation.
ZooKeeper is a centralized configuration service and naming registry for large distributed systems.
Avro is a data serialization system.
UIMA is the architecture for the development, discovery, composition and deployment for the analysis of unstructured data.
The images source for the Icons are from the Hadoop – Apache Project. The only intention of using the images is to showcase the open source tools used by the Hadoop Implementation.
Please visit the following for a beautiful representation of the ecosystem map :
http://indoos.wordpress.com/2010/08/16/hadoop-ecosystem-world-map/ (Thanks to Prashanth for sharing the link!!)
Happy Learning!! 
“It is a high level language for expressing data analysis.”
Pig is not a high level language. Pig Latin is.
Hbase / H-Base should be written as HBase and also ZooKeeper is one word.
Also, for more info, check this:
http://indoos.wordpress.com/2010/08/16/hadoop-ecosystem-world-map
Thanks a lot!! Prashanth for your thoughts and inputs!! Good to learn!!
Wow its a lovely link!!! – great way of showcasing the ecosystem map!!
with best wishes
Pritiman