performance and database improve help

Hi All,
from your experience in SQL 2005 - do i have any free software that can help in improve performance or can help in identifying performance bottleneck. two examples of performance and help that i use usually use are the maintenance plan that do (check DB > reorganized index > rebuild index > update statics) and the second software is the SQL 2005 DASHBOARD for the reporting help.
do you have any other free tools and help that you can give me for performance or any thing that i must have in my SQL 2005 servers.
Thx