I enjoy playing Minecraft with the online applet and the downloaded applet, but I noticed that what I can do with the downloaded application I cannot do to the online applet, such as change the directory of the saves. For example, I play Minecraft off of a flash-drive, and would like my saves to stay there. However, I cannot do this in the online applet. Is it possible to do it, and if so, how? Thank you.
The generic way in Windows 7 (and 8) to the question "how do I tell this application to put its files somewhere else" is to use a junction.
A junction is somewhere between a hard link and a symbolic link (or a shortcut in windows). Creating a junction in place of where you expect the directory to normally go will instead redirect the files sent to that directory to somewhere else.
In this case, we want to create a junction from the usual minecraft directory of %appdata%/.minecraft to a flash drive that is mounted (for example) as E:
To do this, open the run dialog (WINKEY + R) and type
(Make sure the original minecraft directory doesn't exist first).
Now when you run the applet, it will place the files in E:\minecraft.