This highly-rated treadmill from Urevo has a versatile two-in-one design: With the frame up, you can run up to 7.6 mph, and with the frame down, you can tuck it under your desk to walk up to 3.8 mph.
SOLE Fitness (866-780-7653) has upgraded its popular F63 treadmill, which has consistently been rated as the best in its class by numerous magazines and outlets.