Subtitle Master is an excellent tool that makes searching for subtitles a very easy task. It can automatically download subtitles from opensubtitles.org and SubDB. You can start a search in two different ways. Firstly, you can click on "Search Subtitles" in the main application window, which will ask you to select a file to search subtitles for. Secondly, you can drag and drop the file to the application window and the search will be started instantly. I tried dragging and dropping to the dock icon, but that didn't work. Maybe it will in future versions. If Subtitle Master finds a subtitle for the video that you selected, it will automatically download, extract and rename it so that it matches the name of your video file. If the subtitle that was downloaded is out of sync or you simply don't like it, you can click on Search Alternatives to see a list of all the available subtitles found for your file. You can select one from the list to download it.
From the Preferences window, you can choose what language you want the application to download subtitles in. Here, there is also a checkbox that you can check to allow the application to automatically upload subtitles to SubDB. The program probably uses the information about your files to help the SubDB service grow.
In my testing, Subtitle Master found subtitles for most of the files that I tried it with. It didn't have any problems with popular TV shows and movies, but the app didn't manage to find subtitles for a few of my older files. This isn't the application's fault, though. That simply means that the subtitles aren't available on the two websites used by this app.