Heinlein's "Starship Troopers" and "Stalker Analog" by an author whose name escapes me at the moment. Both are excellent. If you are looking for a little bit of Sci-Fi lore, try finding a copy of Heinlein's novel "Beyond this Horizon". It is quite obviously his first adult novel (the plot ends before the book does) but it is interesting to see how his talent developed over time.
You're right though, Fallen Angles is wonderful. I actually own a copy, which is unusual as I normally sell my books back to a used book store.
*nimrod*