Thanks for all the feedback.
Just a few comments and clarifications:
0 for 3 is and always will be broken.
Like lotus bloom?
The only way I can see that remotely not broken would be if you could only use it for activated abilities. It would become another kind of Lion's Eye Diamond.
This could work, but would be a huge nerf. I don't think that there would be any other restrictions necessary than only Activated abilities. Can anyone see an issue with it being worded as Chill79 suggests:
Rainbow Lotus

, Remove ~ from the game: Add three mana of any 3 different colors to your mana pool.
You can't spend this mana to play spells.What if the mana could only be used to play creature spells?
The issue with creature spells and another reason I agree that the initial suggestion was overpowered is the prevalence of viable Zoo everywhere. Just this and no land gives you Isamaru, Wild Nacatl & Figure on turn 1. Or just Wooly Thoctor.
Which brings us back to activated abilities and Anusiens post:
This is the kind of effect that can't ever be fair. Either it's too bad too use or too broken to print.
Land, something, Louts for activated abilities...? How broken or useless can we see this getting?