Top 3

These are three of the best works by Heinlein in my opinion. A photo of each work is on flickr.com; 

Time Enough For Love

Stranger In A Strange Land 

The Cat Who Walks Through Walls 

Each of these photos was uploaded with the Creative Commons license allowing anyone to use or change the photos, as they are simple photos of each book's cover. The tags for each photo are:

1. My blogs address

2. Robert Heinlein: the author of the work in case a search is done by name

3. Science Fiction: for searches done for the genre

4. Books

5. Future History: a classification for a group of his books that are intertwined to a certain extent.