I have been toying with USB disk drives and USB software. I have learned that you can fit an amazing amount of software on a USB drive. I don't know if this is something I mentioned already, but your USB drive can do more than carry music and movies. I have 2 flash drives, each 1GB in size. The first was at one point a U3 flash drive meaning it would bring up that obnoxious "launcher" whenever it was inserted. You can get rid of the thing with this executable. It fixes issues you may otherwise have if you dislike the U3 crap.
On my first Flash drive I have a ton of software installed on it. You can get a ton of open source software for your flash drive at the portable apps website. You can get a copy of Open Office, Abiword, VLC, ClamWin, Sunbird, Gimp, Gaim, Thunderbird, Firefox, NVU, Audacity, 7-Zip, FileZilla, and other software such as Sudoku (which I don't have). I also have a copy of bin2iso file converter. Blender Portable to do 3-D graphics. Burrrn is a portable CD burner. CPU-Z can find info about the PC your running software on. It can show things like clock speed. DD is a useful disk imager for Unix. You can store a portable Windows port of it on your flash drive. A Windows port of the super tiny dillo browser can also run portably. DOSBox can emulate a i386 style CPU with DOS and can be run portably. DiskImage can deal with hard disk and disk information. Easy Cleaner can clean up the Windows registry. eMule can also run from USB. A packet filter firewall also can be useful. A lot of the software from floppy office provides some software that is runnable from a floppy or USB drive. Foobar 2000 is a very sophisticated media player. It can play a wide variety of music. Free Commander is like a Windows style version of Norton Commander. Graph Calc can do 3-D graphs for you. Limewire Portable works from USB, but you may have to reset some of the settings each time you use it and the PC it runs from needs Java. MPlayer is a popular movie player. It is one of the most poplar players on the Linux platform, but there is a Windows port. Make sure you download the Codecs too otherwise MPlayer will just use the codecs already on Windows. Notepad ++ is a popular text editor. More powerful than notepad. OperaTor is a portable Tor (and Privoxy) combined with Opera. PearPC is a PowerPC emulator. It is faster than a traditional emulator but it is still somewhat slow. WinAmp portable is a nice portable media player. Qemu is a multiprocessor emulator. RaWrite images floppies. RazorLame and lame can be run from USB. Sysclean can remove viruses and the like. vMac can emulate the old Apple Macs. You will have to look for roms and disk images. WinVICE is a multisystem emulator. It can emulate hardware such as the C64 and if you can find images, you can play old games, or you can program in BASIC. Bart's Stuff Test can probe for general hardware and software problems. CD2ISO can, well do I need to explain it much further? CDmage can also deal with disk images. CWshredder can remove a certain type of malware. Explore2FS can read ext2/3 file systems. Foxit Reader can read PDFs. FreeCrypt can encrypt files scrabling them with a password. Hijack This is a useful diagnostic tool to search for potential software problems. Media Player Classic is a media player. It looks like Windows Media Player 6.4 but it actually is it's own origional player. Notepad 2 is a program similar to notepad with more features. Opera Portable is a portable version of the Opera browser. Process Explorer is a program that explores currently running processes. Rootkit Revealer can find Rootkits that hide within windows. Skype will run from USB. Stinger can scan for viruses from USB. uTorrent will also run from USB. YamiPod can take music off of your iPod or transfer it on. Most of these can easily be installed as is to your USB drive. Some you must install first and copy it from the brogram files directory to your flash drive.
On my other 1 GB Flash Drive, I installed a copy of Knoppix Linux. To install Knoppix to your USB drive, burn the latest Knoppix onto a CD and boot the live CD normally. Then open up Konsole pop in your flash drive and type:
mkbootdev (you may need to type sudo mkbootdev).
Then you follow the menu and have it set up your flashdrive (it will need to be at least 700 MB, and it will be formatted and erased). Then you will be able to boot from the USB drive, but one thing of note is that old PCs may not be able to. Check your BIOS or if your PC at boot up says hit (button) for a menu hit that to pull up a boot menu.