I have an application that I have written myself available for use. All this program does is automatically poll MtGox at a regular interval and place your entire Bitcoin amount up for sale IF and ONLY IF the price ("buying offer") ever drops below a specified threshold. This will appeal to people who want a safety net for the Bitcoin price, should it ever drop below an undesired figure.
The application can be run on either Linux or Windows and is written in Perl. Please PM me with offers, or contact me directly in IRC (shooter_mcgavin) .