Greetings!
You can find some in the large providers. Here are some I've used:
Commission Junction:
http://www.cj.com/
LinkShare:
http://www.linkshare.com/
ClickBank:
http://www.clickbank.com/
DarkBlue:
http://www.darkblue.com/
Performics:
http://www.performics.com/
MaxBounty:
http://www.maxbounty.com/ (Cost-Per-Action)
Otherwise here is a pretty comprehensive list of providers:
http://www.associateprograms.com/sea...networks.shtml
Is that what your looking for? I was a bit thrown off by the "Pay Per Lead" reference. I don't hear that very often. I'm assuming you're just looking for affiliate programs that will pay you a commission or fee if you're sending them a lead (insurance lead as an example).
Some of the best ones I've found are Insurance WebSites or Financial Companies... and Job Sites like Monster.com (Paid Per Sign Up and for Each Resume Posted)
These programs only require a person to fill out an application or form(lead).
Hopefully that's what your looking for...
There are thousands of such programs. Many of them can be found at providers like CJ.
Good Luck with Your Endeavor!!