When I run home, I use an Inov-8 25l, but leave the office shoes in the office. When I need to carry a small rain jacket in it then the clothes just fit. Without the rain jacket, there's plenty of space for empty lunch boxes, or things like that.
As for laptops: As cougie says, memory stick fits easily.
Hitler plugged blogs? Blimey. I'd always thought he was a bit of a nut job who became leader of Germany, did some stuff that we all think is crazy, and killed a lot of innocent people, but he plugged blogs too? That's really, really is bad.
What shades says plus ... I put ShoeGoo onto new shoes in the areas that I know will wear. I'm sure it looks a bit odd to people behind me ("what has he trodden in?"), but it means the ShoeGoo takes the brunt of the wear. When time, peel off the remnants and re-apply.