Generally I keep my systems pretty straight forward, but I can't live without FruitMenu. I also use TinkerTool for pinning the Dock.
Since last Tuesday I've done 7 installations of Mac OS X. I installed FruitMenu on all of them.
I'm a big Cocoa fan, so services are very important too. I also made sure to install OmniDictionary and Nisus Thesaurus on all of those systems to show off how cool Services are.