Google doesn't take much notice of forum signatures and most forums are nofollow anyway.
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Ian

You need to have a variety of differed backlinks in order to et ranked, forum signature links do help (it's ever the forum in questioned is themed well to your niche).

However forum signature links on their own is a bad idea, you need to diversify, build links for article sites, guest post on high authoriuty websites, or post an article to a themed website similar to yours.

Also for new websites it's harder to rank, google has made it slightly different for brand new websites to rank, so that may be a factor too.
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Industrial tablet PC

The changes made in my opinion are a little controversial because google now looks to see if a site might have been hacked and the potential to be hacked and ranks those sites lower.

They have also added a feature to their webmaster tools that will instantly inform you if your site gets hacked. (I stay far away from Google's webmaster tools as I believe google has secret intentions that really may hurt your rankings if you opt in for it)

1. yes, google change their algorithm on regular basis
2. about google webmaster tools - go for it!!
3. about nofollow backlinks - they count as well, just less important
4. if your site is gone from 1st 500 - it may be put in the black list as well
5. sites mostly fall down because other ones fight for higher spot in search engine rankings

... and of course - a signature in 1 forum is not serious enough

good luck, Helmuts
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Web Design in Maidstone

Maidstone Classifieds

p.s. keeping an open mind

Google change its algorithm at least once a year. We don't know but they do change their algorithm. According to some expert last Feb 2011 is Google's latest update.

New algo change went live in the UK last week, called the Panda update.

I realise this thread is old, but still relevant.
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UK SEO & Web Design http://www.woweb.co.uk

Yes, that Pandora update was pretty major too. You can check out how seriously some websites have been effected here: http://blog.searchmetrics.com/us/2011/04/12/googles-panda-update-rolls-out-to-uk/

worth checking out.
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electronic cigarette ~ http://www.vaping.com/

Google revealed 10 recent changes to its search algorithm today, including one to favor "fresher" results over older content in certain situations. Detection of "official" sites or pages has also improved. Other updates improve search snippets and page titles, as well as info retrieval across languages, among other tweaks.

In addition to the algorithm itself, Google has changed features of the search interface recently. It eliminated the "Timeline" view of results to organize them by date range, and it has integrated Google+ social content in a variety of ways.

Changes Affecting Page Content

Google continues to improve rich snippets and learn how to pull relevant page content into search results. Recent updates make Google smarter about pulling page body content, rather than header or menu content. Others improve page titles by de-duplicating anchor text in links, and improve details in rich snippets for applications.

http://www.whiteroseseo.com/seo-services/


Google has also retired a signal for image search that looked for images referred to by multiple documents around the Web. Another change improves detection of which pages are "official" for a topic or brand.