Wordpress Advanced Category Search/Filter

Hello, I am looking for an advanced search/filter feature to be developed that I can add to my Wordpress website. I wish for this feature to allow visitors to view posts within a category as normal, but to then also have the option to select multiple category tick boxes from 3 separate columns (based on categories and sub categories), which will then filter the posts shown in order to only display posts that appear in the ticked categories. For example: User is viewing category called 'friend' which displays list of all posts under this category. Above the posts, I want options for additional categories to be selected, which then narrows down/filters the post results shown to only show relevant posts. See this image for example - [login to view URL] So, for example, if the category '£10-£50' is selected and also the category 'Sporty', and category 'Personal' then it only shows posts that are under ALL 4 categories (Friend + £10-£50 + Sporty + Personal). (it should automatically know its in category 'friend') If additional categories are also selected, such as '£50-£100' then is will show posts that are under ALL 4 categories again (Friend + £10-£50 or £50-£100 + Sporty + Personal), but with the option of being in EITHER £10-50 or £50-£100 this time! So out of the 3 option columns, the results shown would need to be at least 1 from each column. 'Any' will be selected by default to display posts in any of the categories listed. I would also like it to display the amount of posts there are in real time using ajax if possible, depending on what selections are ticked. (see example above). I am using Wordpress version 2.8. a plugin would be preferred with the option to configure and to be able to place the filter where I want it, but just the code would be fine if not, as long as it is configurable. Hope this makes sense, please let me know if not! Many thanks!