\documentclass{article}
\usepackage[backend=bibtex]{biblatex}
\bibliography{database.bib}
\begin{document}
According to \cite{foo1999} blah blah.
According to \cite{bar1999} blah blah.

\defbibfilter{papers}{
  type=article or
  type=inproceedings or
  type=book
}

\defbibfilter{online}{
  type=online
}

\printbibliography[filter=papers]
\printbibliography[filter=online]

\end{document}