Yesterday at the SQL PASS 2010 Summit I did a presentation on database testing - I have two sets of links I mentioned there, one for the information I presented and the other for various tools I've tried. Enjoy:

More information on Database Testing and Testing methodologies:
http://www.agiledata.org/essays/whatToTest.html
http://www.agiledata.org/essays/databaseTesting.html 
http://www.testinginstitute.com/display.php?id=DATF_MS
http://msdn.microsoft.com/en-us/library/bb381703(VS.80).aspx
http://blogs.technet.com/b/sql_server_isv/archive/2010/10/20/hot-fixes-and-cus-and-service-packs-oh-my.aspx
http://sqlblog.com/blogs/alexander_kuznetsov/archive/2010/10/14/benefit-from-unit-testing-t-sql-speed-up-your-test-harness.aspx
Close These Loopholes in Your Database Testing - http://www.simple-talk.com/sql/t-sql-programming/close-these-loopholes---reproduce-database-errors/
 

Database Testing Tools:
http://www.quest.com/benchmark-factory/ 
http://weblogs.asp.net/rosherove/archive/2004/10/05/238201.aspx
http://www.red-gate.com/ 
http://sourceforge.net/apps/trac/tsqlunit/ 
http://sqlunit.sourceforge.net/ 
http://www.dbunit.org/ 
http://gojko.net/fitnesse/dbfit/
http://www.anydbtest.com/
http://www-01.ibm.com/software/data/optim/streamline-test-data-management/
http://www.turbodata.ca/
http://www.sqledit.com/dg/
http://www.datatect.com/
http://msdn.microsoft.com/en-us/library/aa730872(VS.80).aspx
https://h10078.www1.hp.com/cda/hpms/display/main/hpms_content.jsp?zn=bto&cp=1-10^36653_4000_100__
http://www.radview.com/
http://www.webperformanceinc.com/ 
http://sqlity.net