Recommendations for leak proof containers? I regularly take lunch to work which requires a leak-proof container. The food doesn't necessarily need to be kept hot or particularly cold. An example meal would be a bean salad. 

I am struggling to find a container that is leak proof.  The container will be upended and shaken (not too much!) when in transit from home to work. The container will ideally have a wide mouth to allow me to eat directly from it.

Have you got any suggestions for a suitable container of capacity approximately 500 mL (17oz)?
I hate storing food in plastic, so the best option I found and use myself is http://www.bedbathandbeyond.com/product.asp?sku=112870 which does have a plastic top and silicone gasket but is otherwise glass. Been using for 3-4 years and love them. No leaking problems.