Here are a series of quotes I found from Wizard's Tactics and Tips Series: "Tougher, and Meaner than You" which have some suggestions for the types of snares and traps dragons might employ:
"Green dragons use plant growth to cover up the entrance to their lair, to hide pit traps that surround it, and to make life miserable for their opponents during combat."

"Blue dragons live in desolate, inhospitable deserts full of flowing sand. Their bodies are exquisitely designed for both burrowing through sand and soaring for hours above the dunes. Because of this, parties rarely can use the terrain to their advantage when fighting a blue dragon. Instead, they should be mindful of the terrain so they don't fall into a blue dragon's trap."

"Red dragons live in mountainous terrain, preferably with large caves formed from volcanic activity and boasting tall cliffs from which they can survey their domain. This rocky terrain is typically treacherous for the ill-prepared -- watch out for rockslides (natural and traps), pits, and sheer cliffs that the dragon can bull rush you over.

Old and older dragons make extensive use of suggestion on "allies" to keep them compliant and to coax potential attackers to drop their weapons or walk into the many traps that line their lair. As with the green dragon, if you're talking with a red dragon (a bad idea all around), watch out for odd behavior in your companions."

"Be warned, however, that if you wish it ill, the brass dragon's "waiting room" is a death trap in disguise. If it becomes angered or is attacked, brass dragons (particularly older ones), typically have the roof set to collapse with a simple trigger."

"Adult and older bronze dragons use create food and water mainly to provide for guests, but also to put out food for traps and as a lure for the unwary. While they would never stoop to poison this food, they may set it up over a covered pit or beneath some other trap."

"If you find the entrance to a copper dragon's lair, be prepared for a twisting maze of tunnels, pits, traps, and other 'amusing tricks' on the way to the main chamber."

"Gold dragons make their lairs in any sort of terrain, though they prefer warm plains and always set up home inside places made of stone -- caves, or preferably, castles and other crafted stone buildings. Their caves or castle lairs are designed for both defense and comfort. Welcome guests find these places warm, inviting, and comfortable, while enemies soon discover that they are in dangerous territory, full of traps."
A chromatic dragon may also have a following of kobold minions. Kobolds are vicious little trap makers, so I'd expect to find a myriad of kobold traps protecting the dragon's lair. This article has a number of kobold traps you could use: http://www.wizards.com/default.asp?x=dnd/we/20060127a

In my campaigns, any dragon with a respectable level of casting ability also sets as many magical traps as they can to protect their coveted treasure hoards. Even a lowly spell casting dragon will probably protect their lair with a well placed alarm spell or two. More magically apt dragons can also employ glyphs, contingency spells and illusions to confound potential hoard seekers.

So, traps are definitely an option for dragons. It just depends on the type, intelligence, spell casting ability and available minions. Don't forget that organizations like the Cult of the Dragon in Forgotten Realms can be utilized by dragons to help protect their hoards will magical traps as well.