Here is a free online storage service, offering 50GB of space, 200MB maximum file size. This is by far the largest and best value of the free services. Yes, I said best value and free together. I know. It sounds ridiculous.
This online storage is quite small, with only 1GB of storage, which can grow up to 15GB, with referrals. It has a single file maximum upload size of 25MB. Despite it's limited storage space, it's one of the most popular on the Internet because of it's easy integration with your PC and so many other resources, both online and off.
These guys have been around a while. DropBox integrates well with Windows and various applications. They offer a modest 2GB of space, but beef that up with a healthy 300MB maximum single file size limit. This service allows the largest single file transfers, pushing it way ahead of the others in this category.