The normal solution to this kind of problem is to use some kind of server/network monitoring software.
That is basically a dedicated service running on a server, which will monitor multiple machines (and the S/W on them) via the network. They can also detect whether individual services are up.
See e.g.
http://serverfault.com/questions/44/what-tool-do-you-use-to-monitor-your-servers
http://serverfault.com/questions/1596/application-monitoring-tools
http://serverfault.com/questions/26685/server-monitoring
I have personally used ZenOSS, which can do monitor applications and send alerts, produce graphs etc..
Using a monitoring software for a single app might be overkill, but OTOH it's a standard solution, and most monitoring software is reasonably simple to set up for simple cases, and can run on the monitored machine, so it might be the best solution.
I am not aware of any app just for checking the status of a single, local application.