Red Gate tools (and that was for 11 years before I started to work for them). Other than that, paid tools kind of depends on what you're doing. Monitoring, I'd say Red Gate or SQL Sentry (depending on your size and knowledge). For other work like SSIS, check out PragmaticWorks.

For free stuff, Mladen's software, definitely. I also think that you should look at Ola Hollengren's scripts. Also, as an alternative, check out MidnightDBA's Minion utilities. I think they may turn out to be better. There's Brent Ozar's SQL Blitz scripts. There's Kendal Van Dyke's powershell scripts. Adam Machanic's sp_whoisactive.