During the heat of Summer, the last thing on your mind is, "how can I add more humidity to the air?". If you own a wood burning stove though, now is a great time to pick-up a humidifier and humidistat for a little less.
When you heat with a wood stove, you wick the moisture out of the air VERY quickly. Several times the humidity in my house went so low the humidistat didn't have a reading. This is bad for numerous reasons... it's not healthy, particularly with air-born rhino viruses in the Winter. Moisture in the air will help cling to floating particals and draw them down. Overly dry air will dry out your skin and nasal passages making you more suseptable to sinus infections. Bottom line, get some humidifiers!
Hot steam or cool mist is fine and if the room is pretty large, it can't hurt to have two. More moisture in the air will also make the room feel warmer. You've heard of 120 degree temps in Arizona and the people say, it's tolerable because it's a "dry heat". The opposite is true in this situation, you want more moisture so the room feels warmer. If you have a free-standing woodstove (not an insert), you can place a pot of water on top of the stove for some abient steam. Use this as a supplement though, not a primary form of humidification.
Invest in a humidistat as well. It not only monitors the temperature in the room but also the humidity. The humidistat will give you a visual read-out when the heat/humidity is out of whack.