My favourite trend from SS07 (which I assume will carry onto FW07) is big messenger bags that double as handbags. They are SO useful and cool.
I'm on summer holiday at the moment so I've been able to use my non-school-bags. I haven't bought a bag since last summer so I've hit a bag dry spell. Luckily, my mum bought a few bags for herself and I managed to 'borrow' her Marni balloon bag. I'm really loving it right now. It's SO roomy so it fits pretty much everything in it -when I went to the hair salon, I stuffed a magazine and book in; after I bought skincare products, they fit into the bag too. It's just so convenient to be able to just grab a bag and run out of the house. Plus I love the dark purple -it's the perfect shade of purple to make the bag look pretty, but just dark enough to make it look almost black thus making it versatile. Plus, huge messenger bags seem to go with volumous clothes. Right, I should stop gushing. Here are some others that I found online:
Kooba's Charlie bag from SS07 is so pretty and simple that I can't get why shopbop still has stock (-on sale!) The style reminds my a bit of a less feminine version of Miu Miu bags. And the metal hoops add some detail to the otherwise boring design. 
Urban Outfitters has this canvas convertible bag online. It looks kind of like Balenciaga's motorcycle bag. Think what a great school bag this would make!
I usually don't like Marc by Marc Jacobs' handbags, but it surprisingly has a collection of pretty bags this season. Now this Dr. Q tote would make a fantastic travelling bag because it's huge and soft (so you can stuff the bag into hand luggage comparments.) 
I absolutely adored this Miu Miu bag when it first hit stores last FW. Who knew it would still be around, albeit in different leather and colours? It's super girly yet it's still practical. Why oh why didn't I buy one last FW? 
Because I love this bag so much, here it is in another colour. I can't decide whether a mono-coloured leather version (the one before) is better or this one. There is a contrast between the brown leather and tan kanvas that makes this bag seem more casual and easy-to-use. OK, I'm going to stop obsessing over this bag now -but don't you just love it?
Lastly, I just can't resist tagging on a picture of Ashley Olsen with one of last season's hot bags, Givenchy's Nightingale. I'm not in love with this bag myself but see what I mean about messenger bags? The bag looks so practical and pretty, and you can just throw things in quickly!