search them manually its so easy to do............
go to alexa and check top 500 sites or something like that.
Then check which are forums example:
vbulletin.com
Register create a Profile add your Link in Done..................
Manual this way is much more powerfull as with software like senuke or something like this.
Most people using Cracked Senuke programm but they dont know how to handle this softwares,they do more destroy his Seo on Google and thats not the point of the tools
Trust me make it manually 1 month and you will see what i mean nothing is more Powerful as your Brain and Magic Fingers
Best Greetz