<p>I like Tinkercad so far for it's very simple UI. (I'm new to 3D modeling and very confused by Blender and the like.) However, I'm not using it to do 3D printing just yet. For I'd like to be able to be to slap textures on the models I make and get images of that. What is the easiest beginner way to do that (for Linux OS)?</p>

<p>Alternately, displaying the .obj directly in the browser with a texture would be great, too.</p>

For your purposes, consider that Meshmixer (free) can open .OBJ files and display them in any position you desire.
I use Meshmixer quite a bit for model editing, but have not used it for .OBJ files with textures. I searched my drive and found quite a few .OBJ files, but was not able to present or add textures, due to my own ignorance, I'm sure.
I found a useful link to a
support page
on the 'net which indicates that there has to be a texture file as well as a definition file (.MTL) in order to display the textures in Meshmixer. Using that reference, I was able to add a randomly selected .PNG file and apply the texture to a test model.
If your creations do not include those support files, this may not be a good answer. There's little to lose, however, as the program is free and you may find use for it in the future, or you may find that it works as you require.