I've been using TG Pro since December 2013. Its a great app with a responsive developer. For my usage, TG Pro is more about controlling temperature than monitoring temperatures. It allows the user to lower the threshold at which his or her Mac's fans activate. Apple keeps this threshold on the higher end to cut down on noise pollution, although I seriously doubt their default (around 90+ C) will damage anything. You might want to have a look at iStat Menus as well, however fan speeds have to be adjusted manually in iStat; in TG Pro, fans respond to higher temperatures automatically, you just set it and forget it. I believe both apps offer time-limited trials. I use both on a regular basis and consider them to be worth every penny.