Does a informative and clear professor webpage often increase the number of prospective PhD students who apply to work for the professor? Here is what I would call a particularly informative and clear professor webpage.

Of course, it's not the most important thing (for me, personally, I mostly discovered professors through asking current professors whom to contact). But a lot of PhD students do discover professors to contact through Internet searches, which may be especially relevant for PhD students who might not have as many connections (especially international ones). And maybe a strong professor webpage could also increase the "fit" of the applicants who do decide to contact the professor.
As an international student who is (was?) looking for potential advisors, I'd say yes (As far as I know)! 

The algorithm for me worked as follows:


Contact the obvious ones. These were authors of papers I read recently (&amp; liked), editors of journals etc. Basically, the ones with good "academic presence".
Look at professors who have written textbooks or survey papers.
Look at strong departments for professors. (By strong I mean : Reputation, Rankings and Star Power/Infrastructure)
If a professor has a good webpage (Updated recently with list of current/past projects, list of graduate students and alumni), Shoof! Time saved!
If a professor has a bad webpage (Last updated in 2001 or with minimal content or whatever), then run him on google scholar. Read his papers and try to find out what his students are upto.
Once a professor has been selected, run youtube and ratemyprofessor on him. This is usually worthless but it did yield some awesome results once in a while. It did help get a virtual lab tour at times.


In conclusion:


Maintaining a good website does help students (especially international) get to know the professor better.
It does save us a lot of time by having access to all relevant information at one place
What is most irritating is webpages with very old content. I would prefer limited recent content to old obsolete content.