I agree with your statement Bast, and especially the part about contributing to one's country wich also means being part of a greater community. Here's the model I would like to see for my country:
All young people (males and females) are obliged to serve for at least one, but up to three semesters (6-18 months) depending on their kind of work. The government will ultimately decide where and how people will serve but as much as possible follow personal requests. Education or plans for a future education should be taken into concideration so to make the serving period not a break from young peoples ordinary life but a good and contributing part of their way from adolescent to adult.
There should be a choice between military or civil service. The military of course being the army, navy or air force, while civil service could mean temporary police assignments (directing traffics, search-parties etc), ambulance-driving or other tasks at a hospital, working at the fire department or perhaps as a counsellor or psychiatrist if it's a part of a longer education.
While military service may be tougher and longer it would require less from the individuals when done (unless there is a war of course). Civil service on the other hand would mean the possibility of being drafted later in case of emergencies above "normal", for example natural disasters, traffic accidents involving a great number of people or terrorist attacks (a term currently in fashion).