I used the Orbs of Dragonkind in a homebrewed campaign right at the switch over from AD&D to 3.0.
I used them more like the Orbs from Dragonlance then the ones listed in the DMG.
The Orbs were quest items the party had to retrieve in order to fend off a Chromatic Dragon invasion from a continent that hadn't seen Dragons in ten thousand years. In short, Dragons had passed into myths and legends as creatures of terrifying might and power, but the historical fact was the demi-humans waged war against the Chromatic Dragons long ago with help from Giants (which were then driven off by the dwarves and gnomes). The orbs of Dragonkind were created by a wizards conclave and given power over the specific dragons they called, amongst other powers and were your basic WMD's against the Dragons. The Metallic Dragons saw a continent full of dragon slayers and voluntarily exiled themselves after demanding the orbs were given over to mighty protectors to ensure the orbs would not fall into the wrong hands.
As all good stories go, the BBEG researched the past and deduced the location of one of the orbs, which he used to summon a single red dragon back the continent. Once one showed up, the BBEG worked out a deal and many more appearred.
The group found out about it, and the quest was on to find the orbs before they fell into the BBEG's hand and made him unstoppable.
I still have fond memories of one of the PC's upon encountering their first Dragon (a black dragon) and uttering the phrase, "Look, it's a talking Wyvern!"