CURL

I Changed the CURL Link to the English version.

It could be possible without CURL. In this case you need a PHP Version compiled with --enable-sockets.
Both CURL, and Socket Support shoud be on by default, but CURL for http connections is easier and faster than the socket method.

That my code uses cURL is not a bug - it's a feature, so i changed this issue to "feature request".
The CVS tree from 2006-11-06 has a new function called onlinestatus_fetch_url()
all cURL calls are now there.

if you want you can start to reimplement this function without curl.
just comment out this block in onlinestatus_settings()

//Check if PHP has CURL Support, else drop a message.
  if (!extension_loaded('curl')) {
    drupal_set_message(t('Your PHP installation has no CURL Support, Onlinestatus will not work.'), 'error');
  }

IMHO the best solution would be an "use curl for http queries" checkbox in the admin/settings form.

i replaced CURL with drupal_http_request. So we no longer depend on CURL.