I purchased my first 8Gb USB keychain drive with the sole purpose of installing Ubuntu and booting directly from it.  It wasn't long before I realized that I didn't have a way of testing my backups without worrying about losing data.  (If I backed up my memory stick and wrote the image back to the drive, and the process failed, I would have lost all my data.)

Since the price of flash memory has decreased drastically over the past year, I decided to purchase a second drive.  I attempted to write my backup image to the second keychain drive and dd reported an error, saying that the drive was full.  The backup appears to work just fine, but I wouldn't trust this one as a reliable source.

 At first glance, it appears that my one 8Gb keychain drive is about 1Mb larger than the other one.  My current task is to resize the partition so when I write my image, I don't risk data corruption.

 Some quick research turns up the following process:

1. Run fsck to evaluate the integrity of the ext3 filesystem
2. Run tune2fs to remove the journal (effectively converting the ext3 filesystem to ext2)
3. Run e2fsck to evalute the integrity of the ext2 filesystem
4. Run resize2fs to resize the volume
5. Delete the existing partition
6. Create a new, smaller partition
7. Run tune2fs to add the journal back (effectively converting the ext2 filesystem to ext3)

 I'll note my progress here once I complete the process.