Hi aphaits, the Transform > Orient command can be good for placing an object aligned with a surface normal on a curved surface.

http://moi3d.com/3.0/docs/moi_command_reference8.htm#orient
http://moi3d.com/forum/index.php?webtag=MOI&msg=3424.13
http://moi3d.com/forum/index.php?webtag=MOI&msg=3424.14

Also if you have an object set up in its own separate file centered around the origin you can the ImportPart command which is available by a right-click on the File > Import button. That will bring in that file's content and place it like the Orient command.

- Michael

Or if you want to draw something aligned to a surface normal you can use View > CPlane to set the construction plane to that local frame of reference.

- Michael

Or use the fabulous Orient / Line / Line...my favorite one! :)

Not bad!
Need to play around with it to get it right, the orient command helps a lot!
Really useful for placing screw holes on 3d print models and adding details on scifi hard surface.
Awesome!

Thank you Michael and Pilou!