I am not sure what you are attributing as 'cool' but if it is based on the functionality and not the fact that this is using GWT/Ajax and is open source then you might also want to check useful innovations in the industry related to JMX.
Off-line Diagnostics of Container Runtime State
There are a number of advantages to our approach to inspection and analysis of system and component runtime state information such as JMX attributes.
1. We support off-line browsing of the complete repository (our name for an extension)
2. We collect and structure the repostory data based on natural user access patterns
3. We can go beyond the limitations within the API (JMX) and record complete object field state graphs (mementos)
4. We record all referenced class meta data including code sources, class loaders, interface/implementation hierarchy, annotations,....
5. Data collection is collocated so we do not suffer common performance problems with excessive round trips between the repository sever (JMX MBeanServer) and the console. Collocated and batched!
6. We offer fast and easy access to the on-line and off-line repository from different UI views without the inherent slowness and poor interaction of Ajax based applications.
7. We can collect data from multiple repositories and across multiple processes within a cluster and merge them into a single snapshot or real-time view which is extremely useful for support organizations looking to provide effective and efficient problem analysis.
8. We have more than 25 repository extensions.
9. Repository models support annotation (notes) of the off-line model for improved collaboration across teams.
10. We also support the mapping of JMX attributes (including complex types) to JXInsight metrics. Beautiful Evidence: Metric Monitoring - http://blog.jinspired.com/?p=33
11. Updates to the console in terms of views and analysis inspections work we previously exported repository snapshots.
One current limitation is that we do not support the direct manipulation (setting of attribute values) of each of the underlying repositories. This is likely to change early in the new year.
JXInsight Product Architect
"Java EE tuning, testing, tracing, and monitoring with JXInsight"