Soil thermometers, heat mats and other tools

This is my first year of seriously trying to start seeds indoors. Success has gone to my head with the first showing of little green sprouts! However, I would like to do more than tomatoes and peppers and I know many seeds are somewhat difficult. So, I'm wondering if I should invest in one or more heat mats. And, since I need to direct-sow some seeds outdoors, is a soil thermometer helpful? What tools have you found to be most helpful when you begin starting seeds, indoors or out?

Both of these are a must in my book. If you can afford it, go for one of the professional mats. I just check the beds in my greenhouse and the soil temp is 45 degrees. Not much longer:-)

I used a two-flat sized heat mat this year with a thermostat. It was great for sprouting peppers and tomatos. I bought the mat and thermostat as a kit online. Critterologist has an article under the "guides & information" tab on using bottom heat for starting seeds: http://davesgarden.com/guides/articles/view/556/

David