How many visitors a month do you need to be getting to get below 100 000 rank and this is from your experience. Is the number more then 5000 a month?
Alexa should only be seen as a 'rough' indicator on how a site is doing and nothing else as it can easily be manipulated.
i started my directory 2 weeks ago.. it had a 2million alexa.. today is it 97k i only get maybe 400-500 visits a day. it all has to do with if the person has the alexa toolbar installed.
My Alexa rank is now 95,000 Crossed the 100k borderline just before few days. In my experience, You need at least 3000 Daily Page views to get this rank. But Page Views is not only the matter which determines Alexa Rank. Here is an article for you: http://mextena.com/504-importance-of-alexa-ranking-why-should-we-increase-it.html
It all depends on if they have the alexa toolbar installed. I would think this would cause the more technologically savvy sites to rank higher than other sites. If you have a billion people on the net and 1 million have the alexa toolbar installed, its a good indicator of popularity, but certain people will probably not be represented very well. I have a site getting between 1300-1800 visitors per day and my alexa is roughly 149k for 3 months rolling and 100k for the past week. So it all just depends.
You might get higher ranks for tech sites because only users with alexa toolbars installed are counted towards the alexa statistics.