It is very easy to be intimidated by the amount of info on sites about Tango. Here I include some very useful links that you can explore more. Some of the info is also replicated from site to site like for example if you click this link. Although this link sends you to a Texas site full of references to Tango they are not well structured and information is mostly a collection of links. From this site I choose the next link which is very good and refers to social tango music and what to select.  
Guide to tango Music ---

I find this site to be one of the best amonst its kind TodoTango

Another one I like for the colors used but this site also shows me how ignorant I am from the real culture of birth place of tango is the elportaldeltango although I prefer to look at the spanish version of this site (I look because I cannot read spanish). Also look at this collection at musicargentina but take look at the site as a whole. 

My favorite site is the worst designed blog in the world. But you will find gems if you try very hard. Here are some links in order to see what I mean. Let's start from De Sarli if you go a bit down you will find a link with rar file which includes some mp3's that you will be amazed. Below this link are the other parts of the De Sarli staff. You can collect immaculate staff from this site. The initial page has so much information and more information is put in every month you do not believe it. Ave Tango RBerdi.

In this link you see the greek version of τανγκό στην Wikipedia. The other English version is also here.

Watch this performance. Would I ever?!