My first suggestion would be to write articles and post it on code project and link them in your resumes. If you write good articles, you would get good rating and hopefully win one of the monthly prizes.
For the sample program, try to showcase the technologies you know. You need not do a fancy big ERP package to show your skill, a simple calculator could also prove your object oriented skills. Concentrate on showing how you came up with design and how you solved complex problems. Show any design patterns you used if any and explain the reason to use it. Add unit test showing code coverage if you have that skill. Make the code readable, the interviewer is going to have little time to look at the complete code, try to use SOLID
] and that would help in easy readability and would impress the person reading it.
The first project I did was a simple application to check if the computers in the network are on/off. It was a simple program but impressed my boss. I started adding a lot of features and in no time, I had become a software programmer from the network/system admin work I was doing.
Best of luck in finding your right/dream job.