1) Drive shoeless
Some hardcore hypermilers drive in sock or bare feet so they can modulate the accelerator to the finest degree (particularly important when "driving with load" / "target MPG driving" at cruise.
It shouldn't be that surprising. Race car drivers typically wear extremely thin-sole boots for similar reasons: for the highest level of tactile feedback from the vehicle, and to better finesse the pedals.
2) Conserve momentum: brake hard
It sounds like a contradiction, but there are rare times when braking hard can save fuel compared to coasting or light braking: it's a "damage control" technique when faced with an unpredictable/unanticipated stop or slow down ahead and not a lot of space.
An example: approaching a fresh red traffic light that had no other indicators to predict the change (no pedestrian signal and no cars waiting on the cross street). If you brake lightly/moderately, you will cover the entire distance to the intersection and have no option but coming to a full stop.
But if you brake quite hard initially, you can potentially scrub enough speed and buy enough time to coast the remaining distance to the intersection at a low speed. With judgment and some luck, you'll arrive at a fresh green light and avoid a full stop.
Obviously, rapid deceleration isn't a safe option if there is following traffic.
3) Make fuel economy a game/challenge
Competing against yourself (or others) to get the best possible fuel economy can do wonders for increasing motivation to learn more, refine your skills, and try harder.
Several web sites like EcoModder.com permit you to track and compare your fuel economy against other drivers, and some organize informal fuel economy challenges.
Hybrid festivals (e.g. hybridfest.com, greengrandprix.com) periodically run fuel efficiency rallies where you can hone your skills in competition with others in real time.
4) Use the 'racing line'
Knowing how to pick the "racing line" through a corner, when safe, can help to preserve momentum. Generally, the racing line is the path through a turn with the largest possible radius. It may permit a higher speed with more comfort (less body roll and g-forces), and less tire scrub.
Note this isn't advocating high speed turns, where the cost of increased tire wear may outstrip fuel savings. Even at low speeds, choosing the "racing line" has benefits.
5) Encourage a pass: the fake turn
Drivers who travel below the normal flow of traffic should facilitate drivers approaching from behind to go past safely, with a minimum of interruption.
"Faking" a turn by signalling and moving into a turning lane (even though you intend to continue straight on) is one option.
Note: judgment and care is demanded so you don't mislead any driver into making an unwanted move as a result of your "miscommunication". You must be prepared to actually make the turn if your actions create a situation that would make it the safest option.
6) Encourage a pass: hug right
Drivers who travel below the normal flow of traffic should facilitate drivers approaching from behind to go past, rather than force them to slow down.
One method of gaining the attention of the driver behind is to move your vehicle very obviously to the extreme right of the lane you're traveling in when it's safe for the following vehicle to pass.
Adding a turn signal to the move or the 4-way flashers may be even more effective.
Of course, pulling completely off the roadway onto the shoulder to let following traffic by is also worthwhile, if you have the option.
7) Hill tactic: don't waste potential energy
When facing a red traffic light, or some other predictable stop/start situation at the bottom of a hill, you're better off stopping near the top before you've accelerated to full speed. Wait, and time your release to make it through on green, and you avoid turning your potential energy into brake dust and heat. (Also known as 'smart braking'.)
8) Engine off coasting
Engine-off coasting (EOC) is one of the largest contributors to increased efficiency of hybrid vehicles, many of which automatically shut down the engine when the accelerator is released and the vehicle is coasting.
EOC can be accomplished in non-hybrids as well simply by shifting to neutral and switching the key from "Run" to "Acc" (being careful not to switch to "Off" and cause the steering to lock). As soon as the engine stops, return the key to the "Run" position so the odometer continues to count distance traveled and you're ready for a re-start.
This technique is best suited to cars with manual steering and manual transmissions. (Dramatically increased steering effort may be required in some cars with power assist. Also, most vehicles with automatic transmissions are not designed to travel with the engine shut off; the transmission may be damaged).
In non-hybrids, EOC is considered an advanced technique and should not be attempted until the skill developed away from traffic. In addition, coasting with the engine off is illegal in some areas.
9) Drive with load (DWL)
AKA "target driving". Put most simply, this technique is accomplished by choosing a "target" rate of fuel consumption and ensuring you don't fall below it on hills (or in very strong winds, or any conditions which cause load to vary for a given speed).
In other words, you will back off the accelerator and lose speed (possibly also downshifting) as you climb, and gain that speed back on the descent.
It's far more efficient than pressing the accelerator more and more to maintain speed on the way up a hill and then releasing it down the other side.
DWL is how an efficiency minded person can greatly outperform cruise control in hilly terrain.
Obviously the ability to use this technique without adversely affecting other drivers depends on the traffic situation.
As well, fuel economy instrumentation is required to DWL/target drive to the maximum extent, though it can also be done using a vacuum gauge, and to a much lesser extent by the seat of the pants.
10) Heavy traffic: play the accordion
If faced with worst-case "stop & crawl" traffic conditions, leave as much space ahead of you as possible and continually "accordion" that space to keep your vehicle moving near a constant speed while the cars in front of you stop & start.
11) Pulse and glide
Use pulse and glide rather than maintaining a constant speed, where practical.
12) Push it
If you only have to move your car a very short distance - eg. out of the garage - consider rolling it rather than starting it up to move it.