It is not entirely clear from your post, but I am assuming that this is your first major foray into programming on any platform. Were it not, you would already have access to a stable of your own code on some other platform you could try to port, and this would be a fair way to get experience on a new platform. Furthermore, you wouldn't have to ask here were that the case.
Since you presumptively don't have that experience and code available, porting is not a good way to start. That would just force you to learn two platforms at once.
Frankly, I'd suggest you suck it up and stick with the drudgery of the examples until you have the fundamentals nailed down. Drudgery is a bigger part of software development than anybody realizes at first, and getting comfortable with doing work that doesn't blow anybody's socks off is a lesson in itself. Once you've done the examples, think of minor changes you might make to improve them and figure out how to make that happen, then try to come up with some minor thing that would be useful to you personally. That's way more realistic than trying to write something that scratches a global itch right out of the gate.
At least you aren't starting out wanting to know how to make some great OS or MMORPG you're imagining. That happens a lot, and it always ends in tears. The problem with anything even remotely complex is that it requires picking up several discrete areas of expertise when you really need to be focusing on one.
To write your chat client, for instance, first you need to be comfortable enough with general application programming that you don't have to think about it too much while you focus either on network programming followed by the specific IM protocol you're interested in, or on figuring out how to integrate libpurple into your project. You don't want to be taking all of that on at once.
I'm not trying to be discouraging, and I hope I'm not. The major source of discouragement for new programmers is getting too ambitious too soon. Start small and add one new trick at a time, and you'll get where you want to be.
Good luck!
