If someone has excelled in an area, it'd be a nice gesture to nominate them for an award.
If the letter is being sent as a hard copy, then it should be in the proper business format, otherwise, if the letter is being emailed, it should have an appropriate subject line and proper grammar.
It is with great pleasure that I'm nominating Charlie Beam for the Excellence in Leadership Award. I have been Charlie's manager for the past 5 years and he's always been a pleasure to work with and my most hard working employee.
Charlie was always an outstanding employee; he's the first one to show up in the morning and takes the initiative. In fact he often asks for more work beyond his regular duties and this past year he has volunteered to run the new employee training program.
He is always willing to help out his fellow coworkers by selflessly helping out whenever they need it, often times he'll pitch in without anyone asking him to. By doing this, he's has earned their respect and they've voted him as the employee of the month 8 times over this past year.
I have no doubt that Charlie Beam is most deserving of the Excellence in Leadership Award and give him my highest recommendation. If you have any questions, please don't hesitate to contact me at my office number.