Plain timer is a plain, simple timer for iPad/iPhone/iPod Touch (only for iOS4.0 or later), that can me sure up to 99min:99sec.
You can use it in your kitchen, study-room, and so on.
Even in background, it can work with "notification" feature.
In settings window, you can select the sound from preset sounds, and change its volume.
There's also free version, "Plain Timer Lite" in AppStore, without sound selection and volume setting, and with an ad banner.