Would not recommend mining on a laptop, but if anything I'd say mining primecoins would be your best bet?
I have not heard of a case where a laptop CPU has been overheated in years. The recent Intel CPU's tend to be very reliable. I have had some fun with mine for months, and nothing bad has happened so far.
The Core i7 in my Alienware would disagree with you in regards to the overheating element, although that is obviously not a common scenario
I have it running on 2 threads (every little helps), and it stays below 80 degrees most of the time. If I tried 4 or 6 threads, I'd probably reach 85-100, and 8 would probably force a shutdown. The 7970m running at the same time probably doesn't help...
My VERY old laptop, for kicks, I also have mining litecoin. It's useless for any real-world usage (I think the disk is near-death), but the CPU still runs fine - a Turion TL-52, which is a shame to waste. It's currently putting out a little over 2 kh/s, which is pathetic - you definitely want to target a CPU-only coin, like Primecoin, as previously mentioned by others.