I had mentioned earlier that we are trying to do a lot of biking this summer instead of driving whenever possible. The hard thing about biking is that you can't haul stuff as easily as in a vehicle. We had managed to haul somethings using our trailer, bike racks, pannier bags and baskets but I was still wanting something more. I particularly wanted a very stable place to haul milk (in glass jars) as my parents usually bring us goats milk and give it to us when we are at church.
My solution that worked very well and didn't cost me a penny was to attach (using zip ties) a plastic crate (that I have had for years but only used now and then) to the top of my bike rack. We were able to pack the milk and eggs and other stuff into it carefully and it worked great for transporting it. When we go on bike trips I will probably take it off so that I can use my pannier bags easier but for short term hauling it works very well!