Some links of things I find interesting

Sheet music plus. This is a really big online shop.
Amazon has quite a lot of sheet music in its German and French sites. But you really have to know the language to manage in the sites!
Sheet Music Now. You can buy a wide range of music. You download a file that you can only print once! It’s nicely printed (be certain your printer is OK; you pay anyway!) but they definitely need a corrector for their scores (I wrote this several years ago, this might have improved inbetween).
Every Note. You buy a downloadable pdf file, usually (as far as I’ve tried the site) a scanned version of an old print.

The Sheet Music Archive. Mainly piano music in pdf format. They restrict the number of accesses per session. This is a really fine site!
Johan Tufveson’s site. Unconventional selection of sheet music in ps or pdf format. Mainly ancient chamber music, including the parts for all instruments.
Werner Icking’s Music Archive. Another unconventional collection of music in varied formats, from more typical ps or pdf to Sibelius or Finale.
Empty music paper so that you can write your stuff. Several practical formats. This is a site at the University of Virginia
Variations: Indiana University Music Library. You can look at many old scores on the screen. Not very practical to download: it uses a gif format that prints quite badly.
Choral Public Domain Library. Guess the contents! It has a lot of things for choirs.
International Music Score Library Project (IMSLP), presented, as the CPDL above, in Wikipedia style is another huge project with many things to download.

Music and Musicians (Musique et musiciens), a site at the University of Quebec (part of it only in French), including the detailed catalogues of many composers and links to some sites containing similar information.
Médiathèque de l’IRCAM, a useful website of the IRCAM at the Centre Pompidou, with informations on composers, works and so on.
L’opéra baroque (in French, obviously). Includes a very good list of the most important baroque operas with lots of informations on them.
Musical Resources: Online Guide to the Symphony Orchestra, will lead you to many websites with information (basic and advanced, including explanations on their physics) of musical instruments

Classical Live Online Radio, a site containing links to European and American classical radios you can listen online.
ClassicOL.com includes also a wide list of online classical radios all over the world. Click on the menu “Radio”

Word Reference, an online dictionary from English to Spanish, French and Italian and backwards. Includes a good English dictionary.
The Word Spy is quite fun. It includes explanations of many new idioms and expressions in common English.
German-English dictionary at the Technical University of Munich
The BBC site for language courses and related materials. Some of the activities are great fun.
Fast facts with answers.com. Includes pronounciations of many foreign language names of places and people.

The Internet Movie DataBase. This DB displays a huge amount of information on screen and TV movies, serials and series.
Simply Scripts contains many scripts (that is, the full written text) on movies and TV series. Useful when you get that DVD you want to watch in English and has no subtitles!
TwizTV. Same idea, with an emphasis on TV shows

For almost anything, visit the Wikipedia.
The complete works of Shakespeare are in this link.
World statesmen and Rulers are websites where you can find things as abstruse as who was the Prime Minister of Brazil in 1825, what was the Russian national anthem five years ago and hown many different flags Poland has had in its modern history (please, nobody take offence). Similar things in Zarate´s political collections