For the sister who’s into Harry Potter, have you tried Alivan’s? They have replica wands, Hogwarts accessories (ties, scarves, banners), posters, candy, etc.
I would recommend for your mother a subscription to Soap Opera Digest. As far as the rest go I have no clue, except possibly I would get a gift certificate for a local maternity store for the knocked up one.
Oh, another thing I thought of, since your little sister likes to play The Sims, you could always get her a subscription to a Sims download site, like Simfreaks, or The Well-Dressed Sim. She’d have at least a month’s worth of time to download stuff for her game.
That is a perfect idea!
That is true, but I could still buy her something she likes that she isn’t unnaturally obssessed with.
Hopefully there is an Australian one, because Australian soaps are months behind.
Something my parents difinitely couldn’t have gotten for her! As for your second suggestion, no internet connection 
What about buying your mom something pretty to wear sice she seems to be all about appearance. A luxurious robe like the ones you get at a spa (yes they make them in large sizes too) or a pretty scarf. The point would be something to make her feel nice even if you think it is pointless. Buy her a dvd of Calendar Girls. Get her Bobbie Brown’s make up book, maybe she needs to know how to better cope with aging looks. Most women regardless of thier age want to feel pretty and that they are making the most of their looks whatever their looks maybe. Old and fat isnt’ dead.
You have ideas for your dad and two fo your sisters, can’t really say about the other one since all the information was negative. What was she studying in college?
In my family books are always a good bet, one family memeber is getting the French Laundry cookbook and the Illyad and Odessy on CD, another will be getting a book on identifying birds and a CD of Russian bluegrass, and the other is getting using colors in beading and another beading book as well as gift certificates to a favorite ice cream place and some cookies from a local cookie place. Oh and a booklet on travel for senior citizens.
Ok, thanks everyone for all your help. I now have a fairly definite list:
Mother: a couple of hours at the local beauty place. A haircut.
Father: Bunnings gift voucher (cazzle, do you know my dad?)
Eldest: That containers with supplies is looking mighty good right now.
2nd Eldest: Pillows. Maybe a book on making baby clothes.
Youngest: Still wondering. Probably give her the figurines, then take her shopping.
FilmGeek I didn’t look all that hard, I just naturally assumed that one didn’t exist. But what do I know of society 
adhemar, she was studying science, but to be honest, I don’t think she enjoyed it all too much.