There are some content rotator modules, but that doesn't sound like what you need here. I really don't know if anything exists like you are asking for with regards to your logo, but thus far I haven't seen anything that fits the reqs.

As for your visio like module, I am pretty sure nothing even comes close to this. Actually, outside of mind mapping type web software, I can't think of any web application that does this which isn't custom.

Ventrian has one as does dnndev (Xmod maker) called testify.

As far as online diagrams you could try Mindmeister from www.mindmeister.com - this is more of a mind map program. Or Gliffy is very nice @ www.gliffy.com  I know mindmeister has an api and/or embed. Not sure about gliffy.

Greg