When you're talking about securing a job, what you really mean is "What can I put on my resume?"
The answer is: Any programming project about which your current boss would say, "Yeah, I remember him doing that."
If you can put it on your resume, it's real. It doesn't matter if you're new to the language or not. It doesn't matter if the project was complicated or important. You did it, you got paid, you can prove it. That's all.
Jobless
If you don't have a job, you're just about screwed. Anything you do that a company doesn't pay you for looks like a hobby on a resume. I would recommend making little apps that you can sell to the general public for a few bucks, creating a web page to market them, and list that on your resume. You can also contribute to an open-source project. It still kind of looks like a hobby, but at least future employers can sample your work.
Non-Programming Job
If you work at a non-programming job, there's no reason you can't write code for your workplace. I sold treadmills at Sears. It was difficult to keep track of what was in the stock room. I created a system to help us keep track. Technically, they paid me to do it, so it was professional work. It looks kind of weird because the job title is "sales associate," but if you asked my boss about it, he'd remember it, and say I did a good job. The crappier your current job, the more little bits of software can help. Any shift manager at a restaurant or store would LOVE to have an app to help schedule people's shifts. Doing that by hand is a nightmare, but in code, it's just an overlapping series of rules.
Programming Job
If you currently have a programming job, figure out what technology you want to work with next. (I would suggest the language with the most open positions in your area.) Figure out a side-project you could do in that technology, and do it. If you don't think your boss would approve that project, do it in your own time, and present it as a gift. Your resume will not care if your manager really wanted it or not, and as long as he remembers you did it, it will be real to potential employers.