The Waterfall Drill

This is seriously one of my favorite drills because it looks really pretty when it is done well! It's also mega-effective for keeping jammers behind you, and/or for giving a jammer multiple hits. I've got the three-blocker version here, but you can do it with two or four blockers as well (or do this and have a roving blocker).

Basically, set up as normal and have your blockers take off the pivot line:

As they go into the first turn, they should be heading in towards the inside line. Since the apex is the shortest way around the track, holding the inside line on the turn really prevents jammers from being able to get past. A jammer who takes the outside will have way more work to do to get past the blockers, and it's much easier for a blocker who is holding the inside to quickly go out and hold them up as well.

How you have your blockers on the inside line on the turn seems to vary. I've seen blockers in a staggered pack, (so you have people at 45 degrees in front and behind you) or in a line so everyone is holding the inside, or whatever.

When you get to the straightaway, fan out so that the blockers are more or less in a line (or you can stagger this again to cover more space, but my MS paint skillz are kinda crap). The first blocker should go furthest to the outside. This will cover pretty much all the area on the straight (unless you are me and have really short arms, which makes it easy for a sneaky jammer to get past because I can't be touching my teammates as easily):

On the next turn, the outmost blocker (#1 in the picture) falls back in behind the other blockers, such that they clump together at the next apex:

Again, this way your blockers are taking the shortest route around the corner. Unless you are up against a stupidly fast jammer, you shouldn't have a problem with the jammer trying to get past you. Even if blocker #1 is able to positional block the jammer by herself, it's still strategically better for her to drop into the inside line and hold that, because it's faster. Also, if the jammer speeds up to try and get past the blockers on the outside, the blockers can pretty easily speed up to stay ahead of her:

When you come out of the turn, the last blocker (#1 in the picture) takes over holding the inside line from Blocker #2, and then everyone fans out again for the straightaway:

At the next turn, B3 will drop behind the others and become the inside line blocker and B2 becomes the outside blocker on the next straightaway, and so on.

The rule for this one is to HOLD THE INSIDE LINE. 

The second rule for this is to KNOW WHERE YOUR TEAMMATES ARE. Touch them, push them into position (usually good for the person who is coming around behind the back to replace whoever is on the inside line), talk to them.

This drill takes a bit of getting used to before you know what you're doing, so doing maybe 3-4 rotations makes sense. It's kind of like learning how to do a braid or something: at first you're all like ARGH but once you see the pattern with what your hands are doing it's really quite easy. Similar, once you have the drill going and your blockers are constantly waterfalling and are being really effective with their communication and positioning, it looks really good, like a well-oiled machine. And then it is hard to get jammers through (you can test it with a fourth person jamming behind them)!