I am a beginner level programmer preparing for the interview in medical research company. Job sounds damn interesting and I would like to get there. To show my skills and interest, I want to write a program related to the topic. What would you suggest?
First ideas: simple statistical analysis of input data, image collections, lab inventory program..
I think your question is far too general to be answered here.
Besides that, I doubt that the interviewers will be impressed by a demonstration of your programming skills -- unless you have managed to solve an outstanding bioinformatics problem. You will probably be asked questions related to programming though, where it might be good to read up on general topics (e.g. tree traversal, database normal forms, etc.).
Please do a search on the biostar archive before posting new questions. You may have found this question: What Is Your Favorite Question To Ask When Interviewing Potential Bioinformaticians?