Our dryer vents outside. I am always watching all that hot air blowing outside. Is there a safety reason why dryers vent outside vs. having the heat blown inside?

it's a potential fire hazard. especaily in a small laundry room where lint can build up quickly.
there are kits that you can get that vent your dryer into a bucket thing that you fill with water. the water collects teh lint and sorta keeps it from being a fire hazard, but you have to empty it frequently and make sure it stays filled with water. it doesn't allow the hot air to really do anything helpful like heat the house. it's really just a big pain to keep track of.

We had that system Janie is refering to and it was crap it didn't work at all and everything smelled mildewy all of the time - They are supposed to be creating a new system that vents through a heat "trap" in your wall before it pushes the lint out - but it hasn't been released yet - we are watching for it so we can try it - we would like to use our dryer heat to help offset the heater charge we accrue for warming the weazils and the chickens.

I just found this Q & A on venting a clothes dryer inside the house. Not a good idea at all! :(

http://www.oregonlive.com/homeimprovement/index.ssf?/aroundhouse/stories/19961226intmisc_dwk378_kz.html

I rented an apartment once with washer/dryer hook-ups, and the only vent for the dryer was one of those little buckets you filled with water. I hated all the humidity that was generated every time I dryed a load. I would open a window to try and keep the condensation from building up too bad. I did not like it at all. The washer and dryer were in my walk-in closet in the master bedroom. I had to leave the closet door open all the time to keep my clothes and shoes from getting mildewed.

we vent into our house and have never had any problems. it smells good, but there is a lot of humidity. we burn a wood stove in the winter time and it tends to dry the air out...so they balance well. ;)