The Logic of Chance by Eugene Koonin now can be found on any internet site selling books (and on many other sites as well). This book gives a synthetic (albeit quite personal) view of the modern evolutionary biology. A significant part of the book is devoted to the search for simple and universal biological laws, which would help explain the universal trends observed in molecular data.
The book is wonderfully written, does not require much from the reader, and has a very interesting historical account of the evolutionary theory together with personal remarks from the author.
This book is also invaluable as a source of verbal models of various evolutionary scenarios, which would be very interesting to cast in terms of mathematical models.
Here is a very concise review by the same author, which could be read as a short introduction for the whole book.
Mathematical Biology 