Although the HSK Exam (汉语水平考试 / 漢語水平考試) changed in 2010, I still recommend the website www.hskflashcards.com.
As the name implies, there is a built-in flashcard feature (not Flash-based!). The functionality is pretty basic: you see hanzi (traditional, simplified, or both) and you think whether you know the pinyin and English meaning. Flip to check if you were right and click 对 or 错 as appropriate.
The flashcards are not limited to the old HSK. You can also test yourself on vocabulary from New Practical Chinese Reader, Practical Chinese Reader, or Integrated Chinese (2nd or 3rd ed.)
The interface is pretty slick but not immediately intuitive, so here are some tips:
- Use the sliders to chose the range of words included in the test.
- While testing, buttons for flipping the card, moving forward and backward, marking correct or incorrect, etc. are hidden until you mouse over them.
- You can also use the keyboard instead of the hidden buttons. Click “Help” on the screen to see what keys do what.
There is more to the site, however, than flashcard practice.
If you want to use another flashcard app (if you’re offline or just want more features), visit the Downloads section (again, there’s more than just HSK stuff). Flashcard files are available pre-formatted for Pleco, Mnemosyne, and ZDT, along with PDFs for printable cards. Vocabulary lists are also available in various file formats (spreadsheet, csv, text, xml) which can be used to create cards in other apps or websites. In fact, I highly recommend using another flashcard app or website, as the one provided at hskflashcards.com is pretty light on features. For what I consider to be useful features, please see the page “Choosing a digital flashcard app or site.”
Another section that may not seem like a big deal is the Browse section, but it is the easiest way I’ve seen to browse through the (pre-2010) HSK vocab lists.