I recently got my hands on a fantastic little device called the SD2IEC which allows you to use SD cards as a storage method on Commodore 8-bit machines.
If you're still struggling along with 5.25" floppy disks or even worse, the very slow datassette then using SD cards will massively transform your classic machine usage.
Twinned with a great piece of software called CBM Filebrowser you can navigate and load D64 and PRG files directly from a FAT formatted SDCard. It is possible to access them in the usual way via CBM BASIC but the filebrowser is much more intuitive. There are versions for most Commodore 8-bit machines and can be downloaded for free from here: http://www.vic20.it/cbmfilebrowser/