I've done, and know quite a few people, who are currently selling framework updates (https://railslts.com), a/b testing as a service (https://draft.nu/revise/), and not to mention selling blocks of time upfront — e.g. the retainer model a lot of agencies employ.
(Re)selling hosting, webapps, etc. situates you as a middleman; The margins are much better if you not not only sell them on an Optimizely account, but run it for them also.