http://www.liveaquaria.com/product/prod_Di...cfm?pCatId=1040 one of those?
i had thought about getting one of those but i have never seen them recomended for goldfish but on the other hand ive never heard of anyone saying dont do it.
On the surface it looks okay it grows to 4 inch same as the rubber lip and it is okay for a tropical community and live aquaria say its a good community fish.
If you had the tank heated i guess it could work in theory but id have a spare tank or a back up plan to house them elsewhere if it didnt work out.
If you want somthing a bit different you could try and find an interesting variation of the bristlenose, i have an albino which is lovley

but at the same store they had the light coloured ones dark ones near black ones and even a large spotted male one and that family of plecos are commonly accepted as safe with goldfish

hope ive helped:)
i should probs say im not a pro at all still quite a noob so my advise may be flawed ^^''