There are a variety of materials that can be engraved and/or cut with a LASER.  Here are the most popular:

Acrylic

Due to its beauty and durability, acrylic remains a favorite of laser engravers.  It is typically engraved using low Power and high Speed. This will produce a frosted look. It does tend to scratch easily, so handle with care for best results. Eye catching designs can be gotten by engraving on multiple sides of acrylic pieces such as obelisks, pyramids, and triangle.
 
Glass

Laser Engraving on glass does produce a light frosted look that is attractive and useful for many applications. But beware!  Some glass, that which has a high lead content, may be prone to shattering.  It’s best to experiment and always ask for extra pieces when possible. When you find glass pieces that work well for your application, stick with it. Success in laser engraving glass is oftentimes dependent on the material you choose. Glass is usually engraved at full power and full speed. You might find that extra passes are needed to get the desired results

Marble

Marble is another great material for laser engraving. Stick to pieces that will show contrast and keep in mind, for multiple run jobs, variations between pieces are common.  Marble is usually run at high power and high speed.  Experimentation is recommended, as too much power will result in the browning of the material.

Metals

One of the restrictions of laser engraving is that the CO2 Laser, the most common laser used in the engraving field, is its' inability to engrave on bare metals. However, coated or painted metals do engrave very well using this type of laser. Today's coated metals are especially attractive because they are polished and lacquered prior to applying the outer layer of paint. This results in engraving that is sharp, clean, and customer ready immediately after laser engraving. The lacquering also prevents the engraved area(s) from oxidizing. Coated metal products are generally engraved using low power and high speed. There are also new methods of engraving on bare metals available that allow the CO2 laser engraver to apply a thin paste of a molybdenum oxide, engrave thorough it, and wash the excess off.  This does work well for some bare metals such as stainless steel, aluminum, nickel, chrome, and titanium, just to name a few.

Plastic

There are a variety of plastics that both laser engrave and laser cut with great results. Plastics do vary a greatly with regards to what settings will work best. Equipment manufacturers and suppliers of plastics will provide recommended settings, but nothing beats experimentation in determining the most efficient settings.

Wood

Laser engraved wood is still one of the mainstays of the process. When buying wood for laser engraving, look for products that are sold as laser compatible.  This will assure that any stains, bleaches, oils, etc. used in finishing the wood will not react adversely with the laser.  Settings used for laser engraving on wood will vary depending on wood and desired effect.

Other

There are a variety of other materials that are laser engravable.  This includes leather, synthetic woods and stone, hard surfaced material  (ie…Corian, Avonite) vinyl, ceramics,  rubber stamp material, mat board, paper, cork, fabrics, and gasket material.  When possible, look for products that are sold as “laser engravable”.  This will not only guarantee great results, but oftentimes the material manufacturer will provide settings and other tips for working with their products. You will also want to keep in mind that, while recommended settings can be useful, results will vary. Nothing beats experimentation when it comes to finding the optimal settings for your specific material and products. It is also recommended that you keep up with new product and trends by reading trade journals, attending trade shows and using online searches.