I use DbVisualizer to run complex queries in many databases, including about every vendor with a relational database.
Timed SQL execution and real-time graphs are the killer features. It is a multiple-platform tool, based on Java but with a native look and feel. Most colleagues initially don't believe it is entirely written in Java.
For Oracle, I use it to analyze AWR data.
During database restores, I use this to monitor the progression and to estimate the remaining time.
The limits to its use are by imagination only.