Here I put some useful links.

Astronomy resources

Postscript tricks: Adam's website
Daily astro-ph updates: astro-ph
astro-ph discussion toolkit: VoxCharta
SIMBAD astronomical objects database: SIMBAD Astronomical Database
Astrobetter (and rumor mill): AstroBetter - Tips and Tricks for Professional Astronomers
Discussion of astro-ph papers and more: astrobites - the astro-ph reader's digest
astro-ph discussion in Chinese: Astroleaks - Enjoy Astronomy Everyday!
Radio astronomy course at NRAO: Essential Radio Astronomy
Monthly star formation news and reviews: The Star Formation Newsletter
News, resources, and publication list of astrochemistry: The Astrochymist
Harvard Ay201b course site: ISM and Star Formation
Astronomy (mostly star formation) wiki at PMO: SFIG wiki
Circumstellar disks: Catalog of Circumstellar Disks

Astronomy tools

Molecular spectral lines catalogue: Splatalogue
Intepreting SEDs from YSOs: SED fitting tool
Online object visilibity: Object Visibility - STARALT
Live solar system objects: Solar System Live
LST clock: Local Sidereal Time Clock
GAL/EQU coordinates converter: Astronomical Coordinate Calculator
Reconstructing data from graphs: Dexter for your data
Another option: Plot Digitizer

Python

A Python tutorial for CfA: Practical Python for Astronomers
A Python course for MPIA: MPIA Python workshop
Python lectures provided by Enthought: Tools to Learn and Develop in Python
AstroPython resources: Astropython: Python for Astronomers
Matplotlib quick tutorial: Matplotlib tutorial
Better plotting design for matplotlib: Implementation of typographic and design principles in matplotlib and iPython notebook
Make plots with Python/IDL/Mathematica: astroplotlib
Examples of visualisation with MayaVI: Python for Research - Visualisation
Another example of visualizing 3D electric field with MayaVI: The beauty of Mayavi
XKCD style plots with matplotlib: XKCD Plots in Matplotlib: Going the Whole Way
Common Python mistakes: 10 Most Common Python Mistakes | Toptal
Some useful Python features and tricks: 30 Python Language Features and Tricks You May Not Know About
'Magic methods' of Python: A Guide to Python's Magic Methods
Use Python for Bayesian inference: Bayesian-Python
Quick Python commands in shell: pythonpy
Python plotting contest: John Hunter Excellence Plotting Contest

IDL

A guide to IDL for astronomers: Introduction to IDL
IDL astrolib: The IDL Astronomy User's Library
AICer: aicer - Astronomical Image Compounder
Coyote IDL: Coyote's Guide to IDL Programming
IDL mpfit routine: IDL Curve Fitting and Function Optimization
IDL-Python mapping table: Mapping IDL to Python
Use IDL within IPython notebook: IDL Magics for the IPython Notebook

Miscellaneous

Extreme examples of what you can do with TeX: The TeX showcase
Use Mathematica to make a formula for Sir Issac Newton: Making Formulas for Everything - From Pi to the Pink Panther to Sir Isaac Newton
Mathematica astronomy demonstrations: Astronomy - Wolfram Demonstrations Project
Why should we use A-D test instead of K-S test: Beware the Kolmogorov-Smirnov test!
VisIVO for 3D rendering of astrophysical data: VisIVO Gateway
Display FITS images as 3D surfaces: AAOGlimpse