Some random thoughts that have been percolating over the last few weeks. Think of this as brainstorming.
Developers respect substance over appearance. They are generally introverts who appreciate mathematical truths and avoid political machinations. They care less about who you are than about what you have done. No developer will respect a certificate unless that certificate is backed by something tangible, substantial, and verifiable. Attending a two-day course and passing the corresponding test isn't going to cut it. OTOH if the only way to get the certificate is to complete the 12 trials of hercules, then...maybe.
What works with developers? Look at
stackoverflow.com. Developers are climbing all over each other to accumulate credibility points and badges. They earn these points and badges by demonstrating their competence to their peers. The only way you can get a high rating is to impress the readers of your answers. There is no secret cabal that awards the points, and there are no wink-wink handshakes behind the scenes. (That we know of). It's all based on merit.
So what could we offer? Whatever it might be, developers would have to accept it as proof of their competence, not proof of their attendance.
I've been thinking lately about a system of levels, and grades within those levels. By analogy, you can attain the level of a BS degree with a GPA of 3.1. Attaining a certain level is a qualitative statement of your knowledge and skill. The grade is the quantitative evaluation of how well you achieved the level.
Unlike college degrees, however, these should not be one-shot deals. You should be able to continuously increase your grade (and level) throughout your career.
Grades are some kind of accumulating points. You win these points through a series of accomplishments. Taking a tested course, submitting some code for evaluation, participating in an evaluation pairing session, or contributing to an open-source project might be among the kinds of accomplishments that earn you grade points.
You change levels by attaining a certain grade AND by doing something qualitatively different such as learning a new language, taking on a student or apprentice, leading a team, publishing a paper, getting a high DIGG score on a blog, etc.