I've always wanted to get into mobile application development, and finally got down to writing my first Android application. It is called SmsFu. From my market blurb:
"SmsFu stops junk or spam SMS's from irritating you, without you blacklisting them first. How? It silences notifications when the SMS is from a long number (or optionally, not in your phonebook)."
I wrote this application mainly out of irritation with "Jimmy's Killer Prawns", "Coco Bongo", "Honda Midrand", and other spammers who somehow got hold of my phone number and then started arbitrarily spamming me. I decided that the real irritation was that it got me excited about receiving an SMS, thus leading me to drop what I was doing, only to find out that I've been spammed. While the SMS itself isn't a problem, the notification of these types of SMS was the problem, so I set out to solve exactly that.