If you ever went through the grueling process of re-formatting your LaTeX manuscript to match Nature style, you would appreciate this little trick.
A typical LaTeX distro includes nature package with nature.bst file included. *.bst files govern how the BibTeX bibliographies are formatted. The nature.bst file does not handle URLs well and Peter Komar has hacked the original nature.bst file to remove URLs from the bibliography.
Peter has generously agreed to share his hack with the community. The file naturemag_noURL.bst can be downloaded here.
The easiest solution is to place this file into the directory with your manuscript files and to add \bibliographystyle{naturemag_noURL} to your tex document.
Happy TeX-ing!
Update: Link updated - simply rename downloaded file to naturemag_noURL.bst