When it comes to remote desktop sharing, I do it many time for my clients and sometimes for my friends to, mostly I use crossloop which is an amazing remote desktop sharing tool which lets you connect to any computer remotely and control it, the only thing required is that both the computers which are needed to be connected should be connected to internet.
TeamViewer is another free desktop sharing tool which falls in the same category like crossloop, and now TeamViewer is released as a portable version which you can take anywhere on your portable USB drives. As it is the portable version so it does not require any installation to run.
Besides viewing the remote desktop just as if you were sitting in front of it, you can also make use of the program’s features: embedded chat client, file transfer tool, the possibility of recording the session, support for VNP connections and more
Note: TeamViewer Portable is a stripped-down version of the paid application and therefore lacks some extra modules and functionality.