In response to thk, I would love to see an expansion pack of some kind. Here's what I would like to see in no particular order...
* Additional pictures in sex scenes, especially during "foreplay" such as when the PC rubs the girls and when the girls rub and finger themselves, eg a picture a of becky lying back giving herself an orgasm would be uberhot.
* After spying on Ms Holloway, being able to knock on her door or otherwise interrupt her while she's in the mood to see what progresses from there...
* Something more with Becky's mom Mrs. Johnson?
* If the bathrooms have any relevance, I haven't found it... tried searching everything in all of them (if there is something there, any hints?). Maybe being able to walk in on one of the girls (or the girl's moms) taking a shower, spying on them pleasing themselves, being asked to join in, etc.
* A puzzle solution that allows you to enter the changing room when the Headmaster and Alison are in there, spying on them and maybe blackmailing the headmaster in some way?
* A few more ending variations, such as Alison staying at the party so you can have her, Becky, AND Molly all at the same time, or a threesome with Becky and Alison after leaving the party.
* Having the final sex scenes actually end... only with Molly does it end when she gets tired. With Becky or Alison it seems to only end when you leave, making you wonder if there's something you haven't tried. Getting almost caught by Becky's mom and having to jump out the window, or having Alison's mom walk in to join before an ending would be more satisfying.
* And of course becky's sister kirsty. Becky says they are close in age and do everything together... everything could be fun

Maybe by expansion you meant adding complete new characters, but I was focusing on how to add to and improve the gameplay of an already OUTSTANDING game. Here's hoping there's some additions!