Lingua Franca Nova:

LFN Vicipedia
LFN homepage
LFN Wiki
LFN Disionario
Vocabulo fundal
Elefen gramatica
Elefen syntax
Afisas en elefen
Crea de parolas
LFN Facebook group
LFN tutorial

Linguistics:

Introduction to the Study of Languages
Language Families of the World (maps)
Basic Language Structures
Phonetics
The Origin of the Alphabet
The Evolution of Alphabets
Semantics
Semantics: Diagrams
Componential Analysis
Semantics to Syntax
Syntax
Morphology
Speech and the Brain
Language Development in Children
The Origins of Language
The Development of Language
Language Change
The Evolution of English
The Dialects of English

Traducción al Español: Claudio Fuenzalida

Introducción al Estudio del Lenguaje
Estructuras Básicas de las Lenguas
Fonética
Morfología
Desarrollo del Lenguaje en Niños

Los Orígenes del Lenguaje
Cambio y Evolución en el Lenguaje

Speculation (by an amateur):

European Prehistory
     Europeiska Pre-Historia (i svenska: Weronika Pawlak)
     La préhistoire européenne (en français: Deepak Khanna)
Maps of the Progression of the Indo-European Languages 9000 - 1000 BC
Prehistory of the Steppes
Paleo-Balkan Languages
The Evolution of the Indo-European Language
Phonology of Proto-Indo-European
Krell's PIE Homeland Thesis
Y-dna haplotypes and the Indo-European languages
Native American Migrations

Just for fun:

English Simplified Spelling
The Mars Alphabet