Okay, there's hundreds already, but they all miss the point a bit. A color has three perceptual attributes, Hue, Lightness, and Brightness, (Or HSV, HSL, etc etc)
The majority of the online color schemers only harmonize ONE attribute, Hue, while either ignoring the other two, or leaving it at the whim of the user.
Another thing online schemers ignore is the PROPORTION of color to be used. A color scheme that works for 3 equally distributed colors, is different from one that works with one predominant color, or two predominant colors. The way an accent color works is decidedly different from the way a body color works, and color schemers ignore this as well.
Most color schemers ask for one color, and harmonize the rest based on that. Well what if I have two colors! A client has two colors that must be used, how do I harmonize off of that if I can only input one color?
Okay so I could just ignore the color schemer programs, and do the whole thing by eye, right? That kind of defeats the purpose of these programs existance does it not? Why make them or have them, if in the end they are completely useless?
Todays idea is, a color schemer that isn't a sack of shit.