A note on the ratings I use
Since I'm not American, but Swedish, I don't use the American rating system as my first choice. I'm using the British BBFC ratings instead. (The logical choice would be to use the Swedish movie rating system, but that particular one doesn't really take things like strong language and sexual contents into account, which pretty much would mean everything I write is 7+ or lower.)
Ratings (with US approximative equivalents)
U (G) - For everyone.
PG (PG) - More serious issues allowed; may have mild bad language, natural nudity but no sexual context, implied sexual activity if brief and rare, moderate non-detailed violence if justified.
12 (PG to PG-13) - Mature themes allowed; may have occasional strong language, nudity but brief in sexual context, implied sexual contents, non-detailed violence.
15 (PG-13 to R) - All themes allowed; may have frequent use of strong language, nudity, sexual activities but without strong detail, strong violence but without strong detail.
18 (NC-17) - No constraints contentwise.