Turboboost uses internal storage (system/data/cace) as swap memory, like virtual memory using your hard disk on your PC, allowing you to run apps that need a lot of memory.
Crossbreeder is entropy and net tweaks, such as parallel dns calls and adblock.
Both work well on any rom, and are recommeded.
The only other tweak package I'd recommend would be v6 supercharger with patched services.jar for better multi tasking.
Most of the others tend to be build.prop tweaks etc, device specific stuff and generic tweaks, all of which would already be included on any custom rom. Might benefit someone running a stock rom though. Ususally they cause more problems than it's worth.