Switching it up

If left to my own devices, I would just run about 5-6 days a week. But I have friends and running buddies who remind me that it is important to switch it up. The half marathon training schedule has two days of strength or cross training. I have a few options. I own some DVD workouts and I have some printed workouts from the group I joined at work (so sad it didn't keep going). But I also have Kathy Smith on Hulu. I just bring my laptop into my workout space, log on and work out. This week I also pulled my bike out and went for two rides. I hope to keep this routine up through the summer, perhaps a new habit?
Would love new ideas or websites to visit.