Inspired partially by 7pmanywhere (which has been inactive for few months now).
Users can have zero or more profiles. A profile is NOT a set of personal details, but something akin to a questionnaire with set of labels attached to it. A set of timed questions written by the user, optionally with sets of accepted answers for each. Other users can search for profiles satisfying set of labels. When they find a profile, they are asked to prepare to answer the questions under a time limit for each question and for the entire set (the main purpose of the time limit is make this process as close to a face to face QA).
There are different types of answers: multiple choice, free form, picture, audio and other variants of them. If the user chooses to pick accepted answer for each question, then unless the user answering the question gets it right, no notifications are sent. A straight forward example would be if you wanted to meet someone whom you wanted to smoke with! You would ask the question "Are you a smoker?" providing an accepted answer of "Yes" letting the service filter out those who weren't smokers.
As there are no classic profiles with people's pictures, etc on them, a user interested in such info can ask for them in form of questions (e.g. a question can be, "How built are you?" with a photo as answer).
This service is of course not limited to dating, for instance you could find people to do a job for you and your profile would be sort of an initial interview where you could ask simple technical questions under time limits.
What do you think?