I'm similar to Odhanan in that way, using dragons either occasionally or often in any given campaign. Voted 'often', since overall, considering my relatively short DMing experience, I've used dragons several times. Dragons should, I think, be a prominent part of D&D campaigns, after all.
When I briefly took over For More Than Glory while Emiricol was busy, I had the party be attacked by an adult green dragon, Oruzanthanax, and his kobold minions. They knew they were in a dragon's territory, judging by longstanding local rumors, and they struggled in two battles against Oruzanthanax, though the first battle was easy since it took place in the open forest, and the second battle was tougher in the dragon's den. Several PC near-deaths later, and the green dragon was dead, along with all but one of his minions. The kobold cleric was knocked out and bound with rope, but kept around by the PC gnome transmuter, who secretly made a deal with the kobold during the night, who Raised the gnome's familiar from the dead (it had been polymorphed into a hydra to help fight the dragon, but that just made it a quick and dead target for the dragon's teeth and breath). The kobold cleric was then, unbound as needed for the Raise Dead spell, able to cast Ethereal Jaunt and escape. The gnome may or may not have chosen to keep his bargain, but the kobold didn't take any chances. He might show up again later as a returning villain. Probably with his dragon Raised too (he and the kobold wizard had been using the dragon as much as the dragon thought he had been using them).
In my Oriental Adventures/Rokugan campaign, the party fought a few enraged nature spirits that had polymorphed into the form of Li Lung dragons. Only after the battle did the PCs see the dragons change form into nature spirit corpses, to the PCs' mixed relief.
In my Rhunaria homebrew campaign, the party has had peaceful dealings with the immortal great wyrm gold dragon Kizaraxmallian, but some of their foolish mistakes and rudeness ticked him off at one point and he banished them from his lair, forbidding them from returning before the next time he awoke from another long slumber (if any of them would even be alive then; likely only the elf). He let his aura of dragon-fear wash over the two that had ticked him off, sending them running in terror, screaming, soiling themselves, and generally making fools of themselves (Kizarax has a unique epic feat to control his frightful presence).
Also in that campaign, the party has had some very brief, indirect experience with the ancient red dragon Modorvalkiderax, who burned one's hometown (and most of his family and friends) to ashes years ago, and whose territory the group passed through recently, where they saw him fly over some ruins they had just left the previous day, barely leaving the place in time to avoid being spotted by him. Only one member of the party, a sorcerer, would have had any means of surviving/escaping such an encounter at their current level. The others would have had to resort to begging and bargaining for their lives. One of the party's other sorcerers (they have 3!!!) is seeking lore about his own dragon ancestor, a brass dragon (or was it copper? I keep forgetting which, he rarely brings it up).
The PCs in that campaign have also learned briefly about a handful of other dragons in the vicinity, and are seeking one out, the silver dragon Morunterevaxes, for guidance on their current endeavor. The only other good dragon in their vicinity, to their knowledge anyway, is Vilmiranaevistis the bronze. They've also heard of several evil dragons besides Modor, such as Feraxanmanokhoun the black, Harkalvanorax the red, Solumaviion the white, and the greens named Larinmalaxiir and Degavanalozar with their brood. The party's likely to encounter at least one or two more of these in their travels, and given that Harkal is Modor's son, the party's fighter is likely to try urging the rest of the party to help him slay it as part of the vengeance for his hometown and family. Depending on how soon that happens, the party just may be able to do it, too. Harkal is hot-headed and much younger/weaker than his father.