Not a lot, if you're a woman and your clothes have been designed without any!
Kyle Cassidy wrote a post about this on her blog, back on the 29th April, and I found it re-posted on Swan Tower blog. She also wrote a follow up post on 2nd May.
Basically, she was complaining about the design of women's clothes. Men's clothes almost always have pockets. Trousers, jackets - they all have places for men to keep their keys and loose change and whatever else they want to carry around with them. Some women's clothes have pockets, but a lot of women's jackets have fake pockets - just a flap with nothing inside - and skirts rarely have pockets. (I'm wearing a skirt now that has one tiny pocket at the back - it's almost impossible to put anything useful in it).
This is not a new problem. When I worked at the Children's Bookshop, I used to browse in the quiet times, and I came upon some fascinating articles in bound volumes of old Girls' Own magazines. These are wonderful big books, with pictorial board covers and gilt lettering, and they date from the late Victorian era into the early 20th century.
In one of them, I once found an article which was almost identical to the recent blog post! There were even line drawings of young ladies' skirts with and without pockets, with a plea for a sensible approach to dress making (a lot of girls would have been sewing their own skirts) by adding pockets to keep such useful items as a handkerchief or pair of scissors, or small change when they went out.
It's a piece of advice I heeded when I sew my own skirts - I usually use a pattern of an A-line skirt with built in pockets on the seam. I have quite basic sewing skills, but this is an easy one to do.
When I find myself wearing clothes without pockets, I use one of my medieval re-enactment pouches on a belt - prettier than the modern bumbags, I think! It's very rare that I carry a handbag.
What we need, as we needed a hundred years ago, is for clothing designers to actually think about how women will be wearing the clothes they are making, and what women will be doing when they're wearing them.