Mythbusters host Adam Savage is known for his scissor-lift toolbox, where any tool can be easily picked up without moving other tools around. Instructables user The Engineer As Hero shows how this concept can be applied to a standard zippered toolbag by adding wood and PVC organisers.
This principle is known as 'first order retrievability', and not having to rustle around in a large heap of tools can make you much more efficient. The process is straightforward: use 6mm plywood to create a solid base to make the toolbag less floppy. Add in vertical partitions according to the size of your tools and use cut-down PVC pipe to create slots to hold long handled tools such as screwdrivers and spanners. You'll have to adjust the design according to the size of your tools and toolbag, but it's a worthwhile effort.
First Order Retrievability Toolbag [Instructables]