1) Buying and Blagging Links : this strategy is well known. A Good link buyer will get you links from semi themed sites or from links within the Body.
A bad way to ask is “I found your site while searching for “keyword” and think we compliment each other” .. hmmm really I know my blog ranks for odd stuff and 9 times out of 10 the sites are really really off the mark.
A good way, backlink check your competitors, and manually go to the sites look at the content and style of link, you don’t want to be emailing your competitors feeder sites lol once you have found a backlink, hand craft an email.
Made up example..
saying how kick arse awesome they are and maybe Wordze emails me and says
“hey great to see you using Trellian and Keyword discovery, we think we have a great product in Wordze and would love you to have a trial and maybe update your post about keyword tools” – you’ll have a much better hit rate, or
“I know you are busy and I thought your post on Trellian and Keyword discovery is cool. Is there any way i could PAY YOU to update your post and include MY WEBSITE”
2) Viral Particle Canon imo one of the easiest ways to get links, take the stumble, sphinn, digg crowds etc, if you can pass 100,000 of these people past a website a % will have blogs and another % will blog about your site product etc etc
3) Your Authority Mate, these are the people that can get a link from a PR8 or PR9 for free, tricky to get but once you have one in your pocket, expect your link network to be on the radar…