It would be nice to have API similar to that offered by QNetworkReply:

QByteArray QNetworkReply::rawHeader(const QByteArray & headerName)
void downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
void uploadProgress(qint64 bytesSent, qint64 bytesTotal)
void metaDataChanged()

This would allow to do some more advanced stuff already possible with QtWebKit, like more fine grained progress tracking, collecting information about website (amount of downloaded resources, total size etc.) and other uses.
Perhaps it could be also used for tracking errors and maybe setting / checking attributes (if Chromium uses similar concepts).