Google - the biggest but least relevent search engine on the internet - has been conducting an anti-directory campaign for a while.
It's understandable in a way because most directories are rubbish and simply clones of themselves or the Dmoz directory (so too is Google's own directory), and a great many of them were created to simply make money by selling links and advertising.
That's why Google now insists that sites that sell links should put 'nofollow' attributes on the links so that the googlebot spider doesn't follow them and therefore raise the ranking of the page being linked to.
It's not very fair for us.
Firstly in our subject area we provide much more useful & relevent listings than Google. It has irritated me for years that if you search for our prime keywords 'tour operators to (eg) Estonia' .... the first page of Google.co.uk's serps lists only 2 relevent tour operators. The remaining 8 listings are the FCO advice page, 3 x non-Estonia-specific travel agencies/portals, 1 x specialist operator of stag weekends to Prague (!) and four near-useless directories. In pole position (No 1) as usual, is the BugBog directory which, for every country, lists one or two of its sponsors, Guerba/Intrepid, Kumaka or Explore. Contrast & compare with www.travel-lists.co.uk/lk1est.html
Secondly, despite the fact that we DON'T sell links (it's 'pay for review' and we write the copy) and we most definitely DO vouch for the companies we link to, I have been forced to add Google 'nofollow' attribute to our links because Google's algorithm is almost certainly too stupid to recognise the difference. (We're a directory with a submit form and an e-commerce page....ergo, we must be a vile & evil paid-link directory).
Thirdly, because I only list relevent & useful companies I have ALWAYS rejected out of hand any link-exchange approach (we get them most days). This clearly stated policy has never changed: "It is impossible to get into the Travel-Lists directory by offering an exchange link"....period. Sadly it has always handicapped our ranking in Google because we can't really do any link building....and Google judges the worth of a site by the number of links to it.
Oh well ...C'est la vie. That's Google for you.
(Irritating though, because in the UK we are particularly anal about Google. 75% of us use it for searching. The Americans are more discerning, 55% of them use it. The world average is 65%)
But the final insult came this week when I noticed that Google has awarded us a pagerank of zero. (Traditionally it's been 5 or 3.)
I suspect it may be a temporary glitch while Google does one of its updates.
But I still hate Google....and Google obviously hates us.