What follows is a review of one of the finest pieces of relatively new free weight-training equipment. The "Trap Bar" allows the practice of relatively safe/effective deadlifts and shugs!
Why, some very knowledgeable authorities in the "iron game" have even argued that trap bar deadlifts and shrugs may be a more effective (and safer!) overall strength/muscle-mass builder than either the mighty straight bar back squat or deadlift!? However, before you pass judgement, please read the following...
Now, for starters, let's qualify that the following remarks would not apply to a competitive powerlifter, or Olympic weightlifter, but rather to the trainee seeking a highly effective and time-saving exercise to add to their workout!
The fact that you can start the trap-bar deadlift in an excellent low "get-set" (starting) position, with the tops of the thighs parallel (or even below parallel) to the floor, and that you can pull the bar straight up and back over the heels, is a big advantage over using a standard straight bar for deadlifts. This is because you practically eliminate the arguably dangerous "rounding-of-the-back" sometimes induced by trying to clear the knees with heavy straight-bar deadlifts.
Additionally, because of the low "get-set"/starting position, of the trap bar deadlift/shrug with tops-of-thighs parallel-to-the-floor, or below parallel (you can stand on blocks), the upper thighs are simultaneously worked in practically the same fashion (i.e. over their full range of movement) as in the back squat!
Thus, trap-bar deadlifts/shrugs are arguably a more effective comparable exercise (particuarly with straps for grip augmentation) than either the straight bar deadlift or back squat, in that you are literally combining the benefits of the deadlift, squat, and shrug (i.e. all three!), all into a
single highly effective compound movement!!
For the purpose of muscular mass/size building, this
single exercise IMO works more muscle groups than either the straight bar deadlift or back squat (particularly for high reps.)! As a result, this exercise can be a big training time-saver, in addition to its effectiveness!
The review, and photo, of a typical sturdy trap bar follow...

Aka: The Shrug/Diamond Bar or the Parallel Grip Deadlift (PGDL) Bar
Intro: If you're into strength training, then you'll know that you have to squat and deadlift. But what if you have a fragile back and can't do either properly? That's where the Trap Bar comes in.
Review: This Trap bar was made by strength writer, Malcolm Watson of Scorpion Gym Equipment - sadly, Malcolm has since passed away. So this review is more relevant as a generic commentary, rather than just for this particular bar.
This bar has a decent chrome finish, good knurling on the handles and non-revolving 'Olympic' sleeves (sleeves that are approx. 2 in. in diameter). After nine years of use and lugging it from country to country it's stood up extremely well.
Load capacity? Not sure, I've only ever loaded up to 440 lbs. on it, but it was rock-solid at that weight and looked like it would take double that without a problem.
The Gerard Trap Bar
More Trap Bar info:
History : Invented by Al Gerard, a deadlift record holder in ADFPA (US drug free powerlifting) - Deadlifting 625 lbs at a bodyweight of 205 lbs, and past age 40. The Trap Bar solved his way to training without aggravating old lower back injuries.
Gerard found that the Trap Bar could work his legs and hips extremely well, without aggravating his fragile back. In fact, his Trap Bar training replaced the Back Squat most of the year, even though he competed in powerlfting. He found he could squat 500lbs despite only training in the squat a couple months a year - the Trap Bar kept his legs strong.
The Trap bar has been championed by Hardgainer Magazine, Cyberpump, Bob Whelan's Natural Strength, Paul Kelso and Dr Ken Leistner.
Deadlift or Squat or "Squatlift"? : It's basically a hybrid of the deadlift and the squat. Very similar to doing squats with dumbells, except you can load up far heavier weights. It's a brilliant alternative to the Squat and regular barbell deadlift. Most people find the parallel grip very comfortable. On high rep sets, it can tilt backwards and forwards, but you can solve that with lifting straps. Although, obviously, it's gives your grip less of a workout.
Stuart McRobert says in Beyond Brawn "Do not consider the Trap Bar deadlift as just an alternative to the barbell squat. It is an outstanding exercise in it's own right....The Trap Bar deadlift is the equal of the squat for many hardgainers...
In fact, it has the potential to be the number one productive exercise for many hard gainers"How it works: Because you stand in it, rather than behind it - you can lower yourself down while keeping you back straight - rather than tilting foward like in the barbell squat and deadlift.
Again, I'll quote McRobert : "In any type of bent-legged deadlift with a Trap Bar there are some big advantages relative to the squat:
The Bar is held beneath the body rather than precariously near the top of the spine as in the squat, and thus there is no bar bearing down on you.
Advantages:
(1) Good form is easier to maintain because the deadlift is technically less demanding than the squat.
(2) Spotters are not needed.
(3) No squat stands, power rack or safety bars are needed
(4) The exercise is easily done from a dead stop at the bottom."
(5) For home trainers it's by far the safest way to lift real heavy.
Trap Bar Exercises:
*Bent legged deadlift (aka "Squatlift") - the main exercise as detailed above
*Stiff legged deadlift
*Parallel grip upright rows
*Parallel grip high pulls
*Shrugs - Olympic lifter's staple - Paul Kelso has written a whole book about them.
*Farmers walk - load up and walk as far as you can. A 'finisher' as popularised by Dinosaur Training.
** you can even do overhead presses but will need to improvise some kind of rack to get it up to shoulder height.
Sizes and weights: This particular bar was weighed by British Airways (horrible excess baggage bill!) and it came in at a whopping 77 lbs. The Trap bar was a 'one-size-fits-all' which might disadvantage huge guys or people that lift with a very wide stance - but these days larger sizes are available - Other options are: regular size sleeves and thick handles.
Trap Bar vs. Shrug Bar : What's the difference? Not much. The Trap bar is made under license from Al Gerard - to get around this the Shrug bar is a slightly different shape. It has the advantage of having a little more space inside it, but it's really the same thing. Be careful when buying Trap bars, as there have been reports of quality issues with US made Trap bars. The Shug bars from Watson and FractionalPlates have a great reputation for quality.
Conclusion : An amazing training tool!