Okay, these might not be 'heating up' because they are well known but I thought this list could be those books that are listed in Moderns Most Expensive, Most Watched & Most Bids list because they are on fire and everyone seems eager to buy them.
Harbinger #1 1:50 variant
Saga #1
Thief of Theives #1
Manhattan Projects #1
New X-Men #128
Batman #1
Amazing Spider-Man #361
Thanos Quest #1
Detective Comics #1
Y:The Last Man #1
New X-Men #128
Batman Adventures #12
Chew #1
And to the purpose of this thread here are some books that are starting to break out into more then $10 that are lesser known:
Daredevil #2
Thief of Thieves #2
Uncanny X-Force #2
Elephantmen #18
As always, more can be found here.