TrendWeight now supports those of you in enlightened countries that use the metric system and use kilograms as their primary unit of weight.
In all seriousness, given that more than 20% of active TrendWeight accounts are users outside of the United States, I feel bad that it took me this long to get the changes made. Please accept my apologies for the long wait.
To enable this for your account, go to your settings page and change the weight units from 'lbs' to 'kg'. Note, double check your Goal Weight after you make the change. It should automatically be converted to a roughly equivalent weight in kg, but you may want to adjust it up or down by 1 kg if you don't like how I did the rounding.
A word of warning though: this functionality is hot off the presses, and while I did some testing (and a couple others volunteered to help me out as well), I won't be satisfied that it works flawlessly until a few weeks go by with lots of you using kg for your unit of choice. So... If you see anything odd (places where the UI still is referring to lbs or places where the numbers seem fishy), please email me at email@example.com and I'll try to figure out what is wrong.