Garcianc2003's pinned down the underlying problem: weight. The "port savers" that I've seen are exactly what you describe: short cables, just long enough that they can be connected to a component and have the other end lay on a shelf, such that the only weight on the connector is the connector itself and a few inches of cable. For a component sitting on a shelf, it's a good solution. For a plasma, it may not work as well, as I'm guessing that the ports are oriented vertically instead of horizontally (exascerbating the weight issue a lot) and probably too far from a shelf for the port savers to rest on anything.

There's one company making cables that include a locking clip, but they're pricey and you have to replace a screw at each connector to provide a connection point. I'd probably look to doing something like what garcianc2003 describes: wire-tie the cables to a fixed point. If the plasma is wall-mounted, you could strap the cables to the mounting arm and leave a little slack between there and the plug. If it is stand-mounted, the stand could be a good attachment point.