Now this question may seem obvious, duh -- killstreaks that come one after another like UAV/Counter-UAV/Predator Missile -- but I am talking about sets of killstreaks that unlock each other while you lay around hiding somewhere - or at least work well enough on their own so you need to only get 1 or 2 kills to get the next killstreak. Right now I have Harrier Strike/Pavelow/AC-130 or Chopper Gunner (depending on map). Once I get my harrier I call it in, then go off somewhere safe for my Pavelow to be ready (I can sometimes get my Pavelow from the Harrier's strike, not even needing to wait for the 3rd harrier to start hovering).
Any other Killstreak combos that work well together?