Sick Babies

This has been an especially hard winter for my little almost 9 month old Luke.  He has literally been sick from December until now of varying degrees of severity with a few healthy days here and there.  Have any of you had an especially hard winter with sickness?  Those who haven't battled sickness or who have, what has worked for you?  Do you have an immune system booster you rely on?  It seems there is so little you can do for a baby since it is difficult and undesireable to give them most over-the-counter remedies.  With that said, here are the things that work best for us:
For Congestion, coughing especially croup and stuffy noses the thing that works best at least temporarily is to go into the bathroom & turn on the shower with hot water - the steam really helps loosen the congestion.  We also use a humidifier. 
I love vicks baby rub since it can even be used on little babies. 

So I'd love to hear what works for you!