SQLQueryStress

What is SQLQueryStress?
SQLQueryStress is a free tool for SQL Server programmers. It is designed to assist with performance stress testing of T-SQL queries and routines. The tool automatically collects metrics to help you determine whether your queries will perform under load, and what kind of resource strain they put on your server.

SQLQueryStress Documentation
Download Page

http://www.datamanipulation.net/sqlquerystress/

SQL Nexus Tool

What is SQL Nexus?
SQL Nexus is a tool that helps you identify the root cause of SQL Server performance issues. It loads and analyzes performance data collected by SQLDiag and PSSDiag. It can dramatically reduce the amount of time you spend manually analyzing data.
Check link below for free download:
http://sqlnexus.codeplex.com/Wiki/View.aspx?title=SqlNexusReports