I can make a portable Minecraft launcher.
It can launch your Minecraft game straight from your flash drive.
I can teach you how to make it, right here on this spot.
*Note that this is for Microsoft Windows, not Mac!*
Make a new folder. Rename it anything you want.
On the inside of the new folder, make two more folders.
One should be called "bin", and the other called "data".
Obviously, remove the quotation marks.
Then make a new .txt file.
Open the .txt file and type this in:
After that, go to File, then click Save As (important!)
Rename it anything you want - just make sure you have ".bat" on the end of it.
Like always, don't include the quotation marks.
Now get your Minecraft.exe file and place it in the "bin" folder you made last time.
Then collect your ".minecraft" folder and copy it to the "data" folder you also made earlier.
You should launch the .bat file and it should launch.
This is also a good way to carry your worlds around with you.