Those are Google Sitelinks. You can block them by using Google Webmaster Tools, however they are auto-generated, and can only be remove-picked.
After Google Webmaster Tools:
Sitelinks are links to a site’s
interior pages. Not all sites have
sitelinks. Google generates these
links automatically, but you can
remove sitelinks you don’t want. (…)
Sitelinks are completely automated,
and we show them only if we think
they’ll be useful to the user. If your
site’s structure doesn’t allow our
algorithms to find good sitelinks, or
we don’t think that the sitelinks are
relevant to the user’s query, we won’t
show them. However, we are always
working to improve how we find and
display sitelinks.