If I had to pick just ONE tool or one "thing" in general to do for footspeed, agility, coordination, conditioning, quickness, and the "cool" factor (once you get good) it would have to be the JUMP ROPE. In my opinion, all of the form running drills, agility drills, & quickness drills don't hold a CANDLE to jumping rope - and if it were up to me, all young athletes would learn how to jump rope and jump rope well before ever screwing around with a bunch of fancy drills. If you're a combat athlete - whether it be a boxer, mma fighter, wrestler, etc or even someone just looking to shed some bodyfat for the summer - you can definately benefit from some serious rope work. Once you get the coordination down, using the rope for gpp and intense metabolic conditioning is hands down one of the best ways to get in "fighting shape". Mixed in with calisthenics such as squats, push ups, or more challenging variations such as jump squats, clapping push ups and burpees - you have a complete conditioning workout using little space and a piece of equipment that costs around $5.
The key to getting good at jumping rope is practice, plain and simple. When first beginning, I've found its easier for most people to just count total skips instead of doing timed rounds. This way you know exactly how much "work" you're getting in and can base your progress off of how quickly you can get all of your reps in.
Start with a single rope turn, double leg hop, with your feet barely getting above the ground and shoot for multiple sets of 100 rope turns/hops and eventually you can start alternating your feet, do slalom hops, single leg hops, cross overs, double unders, and a whole slew of variations.
With the jump rope you can use it as a warm up tool and do timed sets in the 2-5 minute range (mixing up intensity and varying your movement) or continue to count total number of rope turns, or use it as a hardcore conditioning tool - doing intervals sets in the 30-60 second range of high knee running, double unders mixed in with cross overs, fast single rope turns, lateral movement, shuffles, etc. The rope is the ultimate tool for agility, coordination, balance, timing, rythym, footspeed, and once you get a hang of it, is one of the most FUN training tools you can use. Its super cheap and completely portable, which is great for outdoor training.
Here are a few progressions with a few different options to get you going...by the way, "beginner, intermediate and advanced" refer to your jump rope training age, not your level of fitness. These are just a few examples, but really there are tons of ways to use the rope. Try the suggested examples, but definately start trying stuff on your own and find what works for you.
Straight Timed Sets: vary speed and intensity throughout the round
3x2 minutes w/1 minute rest or 3-5 sets of 100 total rope turns
3x3 minutes w/1 minute rest
Advanced: 4x3 minutes w/30 seconds rest
Jump Rope Only Intervals:
100 rope turns (fast) + 50 rope turns (easy) x 6 sets w/60 seconds rest
30 seconds high knee running + 30 second double under + 30 seconds fast paced double skips repeat for a total of 2 minutes; rest 30 seconds; repeat for a total of 3 sets
30 seconds high knee running, slalom hops, cross overs, single turns, etc - fast paced
30 seconds double unders
repeat for a total of 5 minutes without stopping.
100 rope turns + 10 jump squats + 10 plyo push ups + 10 burpees x 5 sets
1 minute jump rope (fast) + 10 jump squats + 10 plyo push ups + 10 burpees x 5 sets
50 double unders + 10 jump squats + 10 plyo push ups + 10 burpees x 5 sets