This page features useful linguistics-related links I've found over the years.
IPA Character Picker Need an IPA character that isn't on your keyboard? Copy and paste from here!
Penn Treebank Tags Necessary for grepping with syntax.
Online Etymology Dictionary Great for those who like some language trivia with their smalltalk.
WordNet Over 15 levels of conceptual depth! Great for estimating how closely related things are.
FrameNet Chuck Fillmore's very useful valence dictionary.
Google NGram Viewer Great for investigating the usage history of a word form.
ACL Anthology Enter at your own peril; if it's computational linguistics, it's likely to be in here.
Amazon Mechanical Turk I use this often! Replaces pen-and-paper experiments in the lab.
R Statistical Project Probably the most useful stats software ever. And it's free!
NLP Packages for R Natural language processing addons for R.
MCWord Database Stats for norming words you plan to use in your experiments.
Wordmine2 More stats for words you need to norm.
SNePS The propositional semantic network developed by Stu Shapiro.
Latent Semantic Analysis A method of measuring how semantically similar pieces of language are.
SWI-Prolog Prolog is a declarative programming language. Logicians rejoice!
Learn Prolog Now! A good resource for learning Prolog.
TRALE An HPSG-based augmentation of Prolog for building natural language parsers.
Perl A wonderful procedural programming language for linguists.
Python Does the same things as Perl, but uses syntax closer to natural language.
Python's Natural Language Toolkit (NLTK) To get the most out of WordNet, you'll want this.
TGrep2 An augmented grep that can search through treebank-annotated corpora.