SQL Server Benchmark and Testing Tools

A list of tools are mentioned for benchmarking and stress testing at http://blogs.msdn.com/b/sriramg/archive/2011/06/20/sql-server-benchmark-tools-and-stress-testing-tools.aspx

A few of the tools are listed below. 

SQLIO
SQLIO is a tool provided by Microsoft which can also be used to determine the I/O capacity of a given configuration. SQLIO is provided ‘as is’ and there is no support offered for any problems encountered when using the tool. http://www.microsoft.com/en-gb/download/details.aspx?id=20163

SQLStress
SQLStress is a tool to stress test a Microsoft SQL Server installation. Its main purpose is to find infrastructure problems within an installation. It can also be used for hardware sizing, system tuning or benchmarking. The focus is on simplicity. http://www.sqlstress.com/Overview.aspx

SQL Load Generator
SQL Load Generator is used to run multiple concurrent queries against SQL Server. The user can choose the number of concurrent queries to run, provide different queries, choose SQL or domain accounts, and provide application name settings. http://sqlloadgenerator.codeplex.com/

Hammerora
Hammerora is a free open source tool, so it’s an extremely accessible, quick way to start benchmarking or simulating load. The autopilot feature also makes running workloads fairly automatic. http://hammerora.sourceforge.net/hammerora_mssqlserver_oltp_v2.7.pdf
More details about it are here http://www.brentozar.com/archive/2012/06/load-test-sqlserver/

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 http://www.datamanipulation.net/sqlquerystress/ 
More details about this stress tool http://www.mssqltips.com/sqlservertip/2730/sql-query-stress-tool/