Hey guys, is there a way I can play my save on other computers? Say my work, mates house or whatever?
 
Maybe by uploading my save to the internet then downloading it?
 
Can i put the save on a USB?
 
What is the save and where can I find it?

For single player, I believe your world is tied to your account, meaning you can take it anywhere. 
For multiplayer, your equipment in a server is also tied to your account, but if the server is reset, I believe you leave your stuff.

on whatever computer you are on, download minecraft from and log in using your account info. All your information is stored "in the cloud" so you can load it up at any computer. You can even run it in a browser if you don't want to dl it on a bunch of computers.

" For single player, I believe your world is tied to your account, meaning you can take it anywhere. For multiplayer, your equipment in a server is also tied to your account, but if the server is reset, I believe you leave your stuff. "

Hey there friend. 
 
What you'll be wanting to do is follows: 
 
Press the windows key, then in the "Quicksearch" box, type in %appdata% 
 
Once in there, you should find .minecraft 
 
Go to saves, and copy it over. It will take a long time, however. Despite the fact that the saves are small, they are very fragmented, so theres a LOT of files to xfer. Pop them into the same directory on the machine you want to do it to, and you're good to go! Make sure you overwrite, or backup, as the situation dictates. Bear in mind that the game doesn't have cloud support intergration, so you'll have to constantly update them if you wish to carry on. Hope that helped! Will check back when I get back home later on tonight :)

" @allenibrahim said:

" For single player, I believe your world is tied to your account, meaning you can take it anywhere. For multiplayer, your equipment in a server is also tied to your account, but if the server is reset, I believe you leave your stuff. "

That cant be right because I loaded up Minecraft on my Laptop and it didn't have the world i play on. "

Save files aren't stored in the cloud.  You'd have to copy them back and forth between computers. 
 
EDIT:  Oh, and like Fallen189 said, that can be a pain, because though the total file size of your save folder is probably only 10-ish mbs, it contains hundreds of tiny files, which take quite awhile to copy.  Notch, the developer of the game, did say he was going to try and simplify the save file by the time the game reaches Beta.

Maybe this is what you're looking for (DISCLAIMER: Haven't tried this out myself):
Minecraft save manager

Hmm, thanks guys, I'll try them out :)