Some spelunking reveals that there are. Here is a complete list from the function definition itself:

"StandardName"
"Name"
"AlternateNames"
"PrivateStandardNames"
"ColorFunction"
"ColorList"
{"ColorList", "Sorted"}
"ColorRules"
{"ColorRules", "Sorted"}
"Range"
{"Range", _Integer?Positive}
"ParameterCount"
"Image"
"Panel"
"ColorNames"
{"ColorNames", "Sorted"}
"BlendArgument"
"PrivateNote"

Evaluating ColorData["Properties"] in 10.0.2 returns:

{"AlternateNames", "ColorFunction", "ColorList", "ColorRules",
 "Image", "Name", "Panel", "ParameterCount", "Range", "StandardName"}

This however is also incomplete. Some spelunking reveals that there are more. Here is a complete list from the function definition itself:

"StandardName"
"Name"
"AlternateNames"
"PrivateStandardNames"
"ColorFunction"
"ColorList"
{"ColorList", "Sorted"}
"ColorRules"
{"ColorRules", "Sorted"}
"Range"
{"Range", _Integer?Positive}
"ParameterCount"
"Image"
"Panel"
"ColorNames"
{"ColorNames", "Sorted"}
"BlendArgument"
"PrivateNote"