I guess we are quite keen on engaging with the local community. We have been conducting rather well attended annual workshops (roughly 50 participants) in the hope of fostering engagements with the community at large. However, our experience has been that it is difficult to build a sustainable engagement because it requires a very specific background and the overheads of background building could be high. We have tried to engage the external student community for their B.E. projects but by the time they build the background to be productive, it's almost the time for them to graduate and then the continuity of the project suffers.
All this has forced me to restrict the explorations and give up on the ambition of taking the ideas to their logical conclusion in the form of submitting code patches to GCC. The problem is that in the kind of explorations we want to do, even an adhoc code for experimentation comes late in the picture and a sensible publicly shareable (and understandable) code comes much much later. So I have no clue how to engage with people who can work on this only part time with most of their time and energy being taken away by their day job which cannot be compromised because paapee pet kaa sawaal hai :-)
In any case, I will be happy to give talks and should be able to pitch it at different levels depending upon the interest and the background of the audience. I would be happy if this could lead to a long term association. If there is a reasonable number of people who wish to explore the option of engaging with us, I will be happy to host the talks at IIT Bombay (and they could well be on a Saturday or a Sunday). My Ph.D. students would be happy to showcase what they are doing although I am afraid there is nothing that would look entertaining unless one is curious about the behind-the-scene activities of how programs are made to work :-)
I think the projects with the objective to outreach could be very different. For example a Learning Management System / Course Selector / Admin that could be used by Engineering Colleges that could build an engaged community (I am sure there is still a lot of scope here). Or Civic apps like Public Transport Guide / City Guide, etc. The key would be to build this publicly on GitHub, making students / colleges use the software, enter issues, see code, push patches, have meetups etc. I am sure there could be a lot of ideas in that direction. This might be also a good opportunity to engage the local community and make it production quality. I am sure there would be a dozen of high quality Rails / Django developers who would be happy to pitch in / be associated.
You are right about highly advanced topics though, there might not be enough critical mass around those projects. Here it might be a better choice to engage with tech companies who are working on those domains (which I think are again very few).