Products:
Liquids
Second Skin Spectrum spray
This is a sprayable liquid deadener, you can put it into any paint gun and simply spray it on. If applied in equal thickness, spectrum will work better and be lighter than any comparable mat. All the liquid deadeners require little prep work to get to stick properly. A simple dusting is enough. Also, liquid deadeners are great to use for your fender wells. Doing the fender wells is a great way to reduce road noise. Both spectrum and sludge dry a very dark blue. For all the liquids, 1 gallon covers ~ 40 sq ft.
Drawbacks: As with out liquid deadeners, it has to dry. Depending on the weather and thickness applied, it can take up to 3 days to dry enough to put the interior back in. If applied in equal thickness of a mat deadener on a good hot day, it takes about 6 hours to dry enough to put the interior back in. It can take from 3-7 days to achieve full potential.
Second Skin Spectrum Sludge
This is comparable to mud in thickness and feel. This is great for people who dont have access to a spray gun for spectrum or people that dont have enough patience to put on multiple layers. You can put this stuff on as thick as you'd like. It takes about the same to dry as spectrum, but the thicker you lay it on the more time that needs to be allowed to dry. Sludge is NOT as good as spectrum, but the difference is not noticeable.
Second Skin Firewall
This is Second Skin's best liquid deadener. It is a little thicker than spectrum but not as thick as sludge. All the same qualities. It dries white.
eD's eDead
Buy light blue spray paint, works about the same.
Mat
Peel n Seal
This is a cheap popular deadening material that can be found at Home Depot or Lowe's. It is normally used as roofing material and is asphault based. If you do get this stuff, you MUST prep the area EXTREMELY well and heat up the mat right before it is applied. If the installation is **** near perfect, it'll fall off. This deadener WILL leave your car smelling for a while, especially if you do it in the summer. If you have really hot summers, you might have a reoccuring smell everytime this stuff gets really hot. If you live in really cold temperatures, asphault based deadeners tend to harden up and get brittle, leading to potential adhesion failure. Asphault is very cheap, this is why this and the next few products will be the cheapest products to buy.
Rockford Fosgate's Dead Skin
Buy Peel n Seal, same stuff, a lot cheaper.
eDead v1SE
A little better than Peel n Seal, same asphault based crap though. This stuff isn't as thin as Peel n Seal and sticks much better. It is a little more expensive than the Peel n Seal, but not by much. As with any asphault based mat, it will smell for a week or two after you put it in and if you have really hot summers you might have that reoccuring smell.
Dynamat
Again, a little better then the eDead stuff in both adhesion and application, but a lot less of the smell.
Fat Mat
Fat Mat is a combination asphault/butyl deadener. It is able to keep cost relatively low without having the drawbacks of cracking, melting, or smelling like asphault mats do. This stuff is actually pretty good, especially for its cost, but isn't all that thick.
Raammat BXT60
This stuff gets the nod from a lot of the regulars on this site. It is also an asphault/butyl based deadener. It is thicker than Fat Mat and seems to have much better deadening capabilities than what the difference in thickness would make you think. This stuff can be had for $150 for 95 sq ft if you look around, that price was from the recent group buy that was held here. Basically $1.60/sq ft. Great stuff.
Stinger's Roadkill
A more expensive, all butyl form of Raammat. Not worth the price difference.
Second Skin Damplifier
This is a full Butyl based deadener. It is a little thicker than Raammat and can be had for about $1.85/ft for 80 sq ft for just being a member of the forum on the website. They offer better deals on different forums every now and again.
Second Skin Damplifier Pro
This is the thickest deadener on the market, period. It is almost 40% thicker than Raammat BXT, plus it is all butyl based. It also one of the more expensive options. It is $2.80/ft for 80 sq ft for being a member of his forum.
Dynamat Extreme
Not as thick as second skin's damplifier pro and more expensive...
There are also a wide variety of specialty deadeners from Second Skin for blocking road noises and absorbing panel vibration. Cascade also makes some as well as Raammat has Ensolite. The only ones I have used are Second Skin's products, so I cannot tell you the difference between the brands. Once I have used all of Second Skin's specialty deadeners, I will post my results on here.
Other things worth mentioning:
Great Stuff: Gaps and Cracks
This stuff is an expandable foam that works great for putting in the crossmembers under the hood or even in the bed rail. It reduces both vibrations and road noise. It is not recommended to put this stuff in your headliner as it has the potential to bow out your roof, but under the hood is poses no threat. It will not disolve or melt from the heat and elements. Be careful when you put this stuff on though, IT EXPANDS. Apply a little at a time and be careful to not let it expand out and fall on the engine, its a pain in the *** to get off. Putting a tarp over the engine bay will solve all those problems though.