Seat bags.

[sandra]

Any ideas about where I could find a nice size seat bag? Most of the ones I've seen are so small. I'd really like a larger one.

[Grog]

Topeak makes a 2-litre one that is quite easily available...

[Surlygirl]

These guys make great bags and in lots of colors and sizes.
http://www.jandd.com/bikes.asp

[BleeckerSt_Girl]

You should decide what you want to carry everyday.
Do you want something you can unclip and take with you when you go into a store? Many people have a large bag and a small bag for different types of occasions. Also in cold weather the large bag can carry a jacket, extra gloves, etc.

[sandra]

I have something for smaller. I need something a little larger, like for a lightweight jacket, yes.

Getting all geared up is never ending, but so much fun!!!

[Surlygirl]

Some of the bags are also expandable. One of the seat bags is called the mountain wedge I think and you can unzip the bottom and make it bigger. Of course like Lisa says, you can always get two.