Android: Popular remote desktop service TeamViewer has rolled out a version of their viewing software that allows anyone with an Android and a relatively decent screen to remotely view, control and help out on desktop systems.
How do you control a remote Windows, Mac or Linux system with a mostly touchscreen-only Android? TeamViewer's controls actually cover the issue in fairly clever fashion. You drag with one finger to scroll the mouse pointer around. Your finger point isn't exactly where the mouse pointer is — it's just kind of connected, so you can see both the cursor and your finger. Single-tapping is a left click, two-finger-tapping is a right click, and the controls for bringing up a keyboard, hitting Ctrl, Alt and the other keys are contained at the bottom.
In other words, TeamViewer will do in a pinch when a friend or relative's system needs to be fixed right away, or if you quickly need into your own system for some files you forgot to email/Dropbox. One note: The Android version seems to require that a desktop client run at least version 6, so you may need to have others download the beta versions of their respective viewing clients.
TeamViewer is a free download for Android, but requires a "side" installation — downloading directly and enabling non-Market installations in your Application settings. Grab it from the QR code at left or at the main download site.