I have a list of names I like floating around in my head, but like a lot of people said, it all depends on the dog. Right now my pets are named after other animals, so I'm tempted to keep that theme. It would work perfectly for a Koolie because I'm lame and would have to name him/her Roo. I like a few names from A Song of Ice and Fire for a Dobe. But, timing will have a lot to do with that. If I have any males in the house when I add one I'll end up getting a girl. If I ever found myself with two female Dobes they would be named Tegan and Sara.
The way things look right now, a Mastiff will more than likely be the next dog added. I made the mistake of telling my sister I was thinking of naming him Stitch. She now refers to future puppy only as "Stitch." Hopefully the name fits, because I have I feeling I'll have a hard time convincing her to call him anything else.