Howler

Howler is a very original timer and alarm clock for the Mac. It allows you to set any number of timers that can run concurrently.

Each times is called a "Howler", but you can change the names to whatever you want. A more descriptive name comes in handy when you have multiple timers active at the same time. I guess having multiple timers when you cook is very useful, for example. When an alarm goes off, instead of hearing an alarm sound, you will hear wolves howling. By default, 10 seconds before an alarm goes off, you will also hear a sort of countdown with other animal sounds.

Each howler displays a small window, in which you can add the number of hours, minutes and seconds in which you want the timer to go off. If instead of using this countdown approach, you want to set an actual alarm, you have to go to the menu bar and select Assistants and then Alarm. This will let you type in an actual date for your alarm (day, month, year, plus time). Each "Howler" can be set to keep howling until the user disables the timer, which is a nice way of making sure the user will hear the timer go off. From the preferences menu, you can change the alarm sounds to any .WAV file that you want.