What are the best tools for OSM user Quality Assurance?

Once we submitted change sets to OSM server how we can monitor user history about their past change sets?

All concerning QA is answered here:

For example:
If you want to have a look at user history, you can see your own for example at http://www.openstreetmap.org/user/MalingaGIS/history
For a specific area have a look at Whodidit, e.g. http://simon04.dev.openstreetmap.org/whodidit/

More reports are available at: http://resultmaps.neis-one.org/