XAMPP is like having a little web host company on your thumb drive. If you did have a WAMP (or LAMP) application you wanted to run, it would make more sense to put it on your web host instead of a thumb drive. But since we can, let’s try to rationalize it.
Localhost is faster.
Localhost is more private.
Localhost is disconnected.
Localhost doesn’t cancel your account when you go-over your download limit.
Localhost is free. If you are the only one using your web host account, maybe you should just blog to your thumb drive.
The above are all handy for using Zena as a streaming media player, which would be slow, not 100% available and expensive in terms of bandwidth if you put it on your hosted account. On the other hand, given that you still have to use Itunes or Windows Media player to play the streaming files, you might as well use then to read the files direct from the thumb drive—the only difference would be the folder browsing.
I couldn’t bring myself to install any personal information management (PIM) type applications. I’d rather have those on a connected server. If data loss didn’t worry you, then you might consider time trackers, address databases, etc. These PIM apps were never very compelling before web 2.0, now they are much more compelling as multi-user social applications.
Speaking of folder browsing, most web-based file browsing system suck, but if one existed that didn’t suck, it would be nice to have that on portable XAMPP. Right now if you want to search your thumb drive, you are stuck with the host OS’s search. IF you use Fast File Search, you can index your thumb drive—indexing it via the FileZilla FTP server is probably superior, since the drive letter will keep changing if you index file system directly.
XAMPP is handy as a development environment. If you are a typical geek, you spend 8 hours in front of your work machine, but outside of the office you might be at your home machine, a laptop or visiting family when you have time to write code. Install Flyspray to maintain a more secure and better performing bug tracker. I still don’t know of a good portable source control server, but you can use RapidSVN as a portable client. You might not want to program in PHP, the asp classic of the curly braces world, you can get portable ruby or Instant Rails. (Instant rails comes with yet another copy of MySQL and Apache, so if you are already using XAMPP you will have a merging project to do.) And if you are really ambitious, you can try to get ASP.NET to work on XAMPP. Try mod_aspdotnet.mo or Grasshopper.
You could lose it.
It isn’t globally available like your web host.