Kiwi-developed social networking site iYomu launched today, and revealed its cunning plan to attract millions of users from all around the world: a puzzle competition with a $US1 million prize - top be decided by a popular vote.

New sign-ups will get the option to try to crack a series of 12 cryptic puzzles, with the ten most successful punters listed on a real-time leader board. When the competition concludes 20 weeks from now, on Dec 31, the top three puzzle solvers will each get to make their case to iYomu's members, who in turn will decide which deserves the cash.

Now, having participated in that TV program that let you rate your IQ, I know that at 160 mine's very high (I think; I got a bit confused at the end when they explained how to add up your score). But if you're thick at puzzles, iYomu will also give you the equivalent points to cracking one of the 12 levels if you refer two friends, or complete your profile.

Developed in Auckland but aiming to gain a tens of millions-strong global audience like Facebook et al, iYomu reckons it's found a niche as the social networking site for grown-ups. Other differentiators (besides the lure of all that lettuce): no banner ads, and 1GB of free storage for back up or sharing music, photos and videos. Read more about its founders, and their vaulting ambition, here.