It mystified me when I first came here too, but now it's just a way of life. I can't imagine nor do I find time to deal w/heat. I remember doing my hair for 3 hours every week before /images/graemlins/nono.gif. No more. My airdry styles are so cute and the way I'd always envisioned my hair being. So I'm happy. I went for 7 mos w/no heat and I swear it's like I have a new head of hair. No splits, no broken pieces when I stroke it, it's strong, supple and has wonderful lustre. I can't wait until I can cut off about 7" of the old stuff that was heat exposed. I only use the Chi iron now for dusting my ends every 8-10 weeks and only after it's already been rollerset so the heat exposure is minimal. Other wise its no heat (air dry) or indirect heat (bonnet dryer on low).
If you are relaxed you have a serious advantage here. You don't need the heat really to rollerset. If you use the largest rollers that wrap your hair around 1 1/2 times you'll have a bend in your hair or hair that just hangs straight. I just bought a bonnet dryer so I'm all excited about it. I use it on medium for 15 mins, then low the rest of the way. And since I don't use setting lotion my hair just comes out straight, but big since I use low and am texturized, not fully relaxed. But then I wrap it and it's smoothes right out. If you wrap (and can wrap well, unlike me) and then sit for another 30 mins you get bouncy hair that's straight and looks like a wrap.
There are other methods, like the ponytail method I think Lindy uses and ArmyQT. They secure the ends to the opposing side of the head and results in str8 hair as well. And it doesn't require heat either.
~SC