This rating system is directly from All Romance Ebooks :) I figured that it was good enough for them, so it's good enough for me. I also sometimes use the movie rating system in my posts which are easy to understand as well.

• 1 flame: Stories will either not have consummated love scenes, or if the loves scenes are consummated detail is not given.
• 2 flames: Stories will have some love scenes. These will be more sensual then graphic and will mostly rely on euphemism.
• 3 flames: Stories will have sensual, yet more explicit love scenes, and the language used to describe them may be more graphic and direct.
• 4 flames: Stories have frequent love scenes that are explicit and described using graphic and direct language.
• 5 flames: Stories have a high frequency of love scenes that are explicit, described using graphic and direct language, and/or contain subject matter that some readers may consider objectionable.