"Friends don't let friends skip Leg Day." One to three days a week can be devoted to your lower body, and how you do it depends on whether you are a runner or other athlete (see Tim Ferriss' 4-Hour Body). I recommend devoting at least one day a week to an intense Leg Day routine.
One simple method is the Faleev model of doing deadlifts and squats. I found this problematic to do at home, however, because I don't have a squat rack and generally just didn't enjoy deadlift-only days.
So, here are five that I do at home that I highly recommend, in the order of intensity and recommendation:
1. Fitness Blender's Mass Workout for Legs (free, Youtube). 35 minutes w/out warmup,stretch.
This is the most intense you-will-be-sore-tomorrow Leg Day routine I do. Daniel uses a barbell but for most exercises you can also use dumbbells. He moves quickly through 4 super sets:
4 Groups of 2 exercises
Three times through per group
Hip Raises (go for 10-12 reps)
Group Three: (I usually switch to dumbbells on the third time b/c my neck hurts).
Calf Raises (go for 10-15 reps)
Single Leg Squats*
Squat Jumps (go for 10-12)
* I like to modify the single leg squats using Tony Horton's Accelerated workout's Warrior 3 squats (see below), so it's 15 reps on each leg each time.
2. Jillian Michaels Killer Buns & Thighs. (This is available for streaming on Amazon).
Level 2. Level 2 is harder than Level 3, especially if you modify it just slightly with weights where Jillian doesn't use them. This is a combination of resistance and plyometrics. A 40-minute workout that sets my heart rate monitor off toward the end as I hit what it thinks is my max heart rate (Insanity doesn't do that). You'll need a chair or bench for doing steps (add weights) and a pair of dumbbells.
Trust me, it's worth it.
3. Fitness Blender's Brutal Butt & Thigh Workout- Drop it Like a Squat! (free, YouTube)
5 Groups of 2 Exercises
AB / AB Format
30 Minutes Total (no warm-up)
What makes it slightly harder are the "active rests" in which you can jog, do burpees, or other cardio to boost your heart rate.
4. Tony Horton's P90X3 DVD Workout - Base Kit
It is not as intense as Eccentric Upper, but is a 30-minute resistance workout with dumbbells (or bands) for lower body that works well. Focus on your form. I recommend adding some ankle weights for the pilates-style part at the end. I use the warmup from this workout for all of the routines above.
5. Fitness Blender's Butt and Thigh Workout - Cardio, Plyo, Pilates and Strength Training Workout for Lower Body (free, YouTube). 35 minutes, warm-up/cool-down included.
6 Groups of two exercises
40 Seconds on, 15 off, X 2
I recommend using heavier weight, like a barbell, for the weighted bridges.
Definitely recommend ankle weights for the pilates-style leg lifts at the end.
6. Tony Horton Accelerated Lower Body Workout (free, YouTube).
Just 5 moves, 10 minutes to do.
I will sometimes add this to all the above. Light dumbbells are helpful.
DS Double L
Warrior 3 Squats
Sumo Squat Kicks
Bounding Split Squats
7. P90X Legs & Back
This routine is more intense for the pull-ups than the leg routine, but it's still good. If you have an hour of time and a pull-up bar, go for it.
What do you do for Leg Day?