Your user profile
Feel free to promote any projects you like in your user profile. (Though it looks like you, wolf_math, have already.)
I recommend that you read the Help Center post on "How not to be a spammer." It indicates that it's fine to make references to your project, within reason, in Q&A posts that you write, as long as you disclose your self-interest there. The most important aspect, in my opinion, is to make sure that the Q&A posts stand on their own as worthwhile and fitting, and that the references to your project are genuinely relevant.
Mi Yodeya chatroom
There's nothing wrong with promoting your project, especially if it's Judaism-related, in our main chat room, V'dibarta Bam. Of course, do keep it within reason.
Community promotion ads
You may post a proposed ad for your project as an answer to the current Community Promotion Ads post. (See there for requirements.) If the community expresses sufficient support for it (by voting it up to +6), it will automatically go into the rotation of ads that run on the sidebar of the front page.