There are a large number of Islamic articles on the internet. In fact it is quite heartening to see such a dynamic Islamic presence on the net. However, since the quality of articles is uneven, exercise your judgement by checking for compliance with, and adherence to, the Quran and (authentic) Sunnah. (One can also try to check your facts with a knowledgeable person like an Islamic scholar). There are articles on tafseer, Quran, sunnah, fasting , hajj & many other topics are available at the following internet sites:

There are a number of articles at this website . Look around.

"Easily Understand Islam" is one of the best books available on Islam . For example, there is an chapter on a contempory topic: how Islam views the environment.

Large collection of Islamic articles at Islamworld. There is a nice one for those mathematically inclined on determining qibla direction.

Large general Islamic website at Islamicity

The MSA (Muslim Students' Associaton) at USC has a collection of assorted articles.  There is an interesting one on hadith classification.