Just a few quick .NET samples for performing some common tasks that the .NET Framework doesn't do for you:

System uptime

using System.Diagnostics;

public TimeSpan GetUptime() {
    PerformanceCounter systemUpTime = new PerformanceCounter("System", "System Up Time");
    systemUpTime.NextValue(); // Required to work!
    return TimeSpan.FromSeconds(systemUpTime.NextValue())));
}

Calculating age

public int GetAge(DateTime birthday) { 
    int years = DateTime.Now.Year - birthday.Year;
    return (birthday.DayOfYear >= DateTime.Now.DayOfYear) ? years : years - 1;
}

Rounding to n decimal places

public decimal ArithmeticRound(decimal d, int decimals) {
    decimal power = (decimal)Math.Pow(10, decimals);
    return (decimal.Floor((Math.Abs(d) * power) + 0.4m) / power) * Math.Sign(d);
}

[)amien