The question What free programs should every GIS user have installed? (previously called "What free programs should every GIS user have installed?") was recently edited to include cloud software.
The precedent appears to have been set by the many upvotes for ColorBrewer, although almost all of the other answers are for desktop software.
Please vote for the appropriate answer if you think cloud software should or should not be allowed in answers to this question, or if you have any other suggestions on how to handle this.
My concern is that cloud-based services are almost never truly free, because cloud computing is expensive. Often you will be asked for credit card information and automatically billed if you exceed the limits allowed in the "free tiers" that are often offered. Additionally they may be ad-supported and generally it is harder to evaluate cloud services than desktop software because you usually have to sign up for something to use them.
My personal preference would be to limit the question to desktop software, for the aforementioned reasons, and have "free" cloud services be suggested in a separate question.