By sleeker do you mean low profile city car, or off-road vehicle? Ebay has a lot of mods. Depending on your taste...
-Headlights - projectors or other aftermarket
-Tail lights - smoke
-Suspension boost
-Tires make a big difference in a vehicles appearance
-White face gauges??
-A "NObama" sticker on the rear window
-Brushgaurd
-Custom grille color or design?? (some people like billet grilles)
-Mcguire's 3 step wax (lots of work - nice results)