With the current version of BlackBerry 10 we of course get an alarm clock, but as yet multiple alarms are not supported. Alarm X for BlackBerry 10 allows for multiples and a whole bunch more and it's a really nice native BlackBerry app.
There isn't a limit to the amount of alarms you can set with Alarm X - and each one can be named so you can also use this as a reminder app if you so desire. As well as each alarm having a selection of sounds you also get something quite unique in the fact that you can even choose which color the LED will flash when the alarm goes off.
In addition, you have the option for vibrate to be enabled - that's sure going to wake you up! With both landscape and portrait modes available there is also a nice standby screen which shows hours, minutes and seconds plus the time of the next alarm.
Due to the current BlackBerry 10 API's you will need to leave Alarm X open as an active frame in order for it to work, but the frame itself is pretty nice and displays the next three alarms.
Priced at £0.75/$0.99 Alarm X is a bargain if you ask me. I've been using it for a few days now and it does a great job.
More information/Download Alarm X for BlackBerry 10