I have a fair list, although maybe not that many. I assume I won't making virtually all them but like to think I can look at them when working out mechanics in games I will make and find some inspiration.

When I have a lot of mesh data, I do have scripts I can run to pack it for quick loads; otherwise it is all OBJ.

More along the lines of the former. I do a lot of config in spreadsheets (hence why it is there to) and export it to a set of xml files which load on launch. Internally it setups definitions to build the animations is instanced. The data is super small, so I can be lazy with formats.

For my current projects, there is a sheet that references meshes (w/in files) and animations (described in the spreadsheet). The animations are composed of a set of keyframes that describe time and some basic transforms (translation, rotation, scale, visibility and pivot for rotation).

I really just use it for building meshes and some basic materials. It is either done purely in code, or through a spreadsheet which is exported for the animation system. Not a particularly good system (and up for replacement), but it does what I need which, like I said is pretty minimal :)

I use Wings3D + some scripting. My needs are fairly minimal and it gives me only what I need. If I ever did need something more elaborate I would contract it out.