Question: What are the query browsers for DB2 e.g Database Administrator(Data Studio), Toad for DB2 etc? I worked with them but are there more ?

Answer: 
You can find a list of browsers in Wikipedia: 

<http://en.wikipedia.org/wiki/Comparison_of_database_tools#General> 

and look at "Other" column. You will see which tools work with DB2.

The popular ones are:

* Toad for DB2 <http://www.toadworld.com/products#ibm-db2>
* SQuirreL <http://www.squirrelsql.org>
* SQL Maestro <http://www.sqlmaestro.com/products/db2/maestro/>
* Altova DatabaseSpy <http://www.altova.com/databasespy.html>
* Embarcardero PowerStudio for DB2 <http://www.embarcadero.com/products/db-powerstudio-for-db2>

Or

* IBM Data Studio (Free) <http://www-01.ibm.com/software/data/optim/data-studio/>
* Technology Explorer (from IBM, on PHP) <http://sourceforge.net/projects/db2mc/>
* Control Center (Deprecated, included in IBM Data server client)
I've recently discovered DBeaver (<http://dbeaver.jkiss.org>) and I love it.
Runs on Win and Linux (on Centos7 I just unpacked an archive and ran executable), it's open source and without need of external driver it has connected to DB2 server right away. Same for PostgreSQL and MS SQL Server. 
Not sure how it compares with other in feature set though, but user experience compared to previously used Squirrel is amazing.