From ST-WARE Softworks:
FileFiller is a small and stable utility, which lets you to create files up to 4GB on FAT partitions and up to 80GB huge files on NTFS partitions. The files can contain either pseudo-random data, or zeros, or they can be filled with an ASCII decimal ordinal value you can specify. Runs on any Windows operating system. The application is multi-threaded, the file creation process is shown on a progress bar and can be cancelled anytime. You can freely set the file-creation-thread's priority and control the physical memory allocation for creating huge files (using the Gigabytes option) from 64MB to 512MB. Auto detects the target drive's filesystem and free space, shown in either megabytes/gigabytes and in percents.