I would like to know how to market products that are very flexible and are not attached to a particular business niche.
For example, Spreasheet software: You can do almost anything with it... balances, payroll and tax calculations, statistics, math graphics, catalog your mp3+dvd collection and even project planning.
In these kind of software (being like a hi-tech version of a paper notebook) the point is the flexibility of the product. So, if it is useful for almost anybody and in multiple scenarios, how they are/should be marketed?
In my experience (I have the scars), the more generic the product, the tougher it is to market. Especially if you are a small company with limited marketing resources. If it is does everything, it effectively does nothing. Even if the product is very generic, I recommend you pick out a particular feature and vertical market and concentrate on those. For example the first spreadsheet was sold to accountants as a way to add up columns of numbers.
I have similar problem. My solution is to focus on 3-4 particular niches and create products that have similar base, but a little customization for each niche.
Customization can be: documentation, terminology used in web pages and marketing, custom interface specific for certain tasks, additional small functionalities specific to given niche.
Main point to remember is that clients do not want software, they want their problems solved. So you create solution for problem and they buy it.
There's nothing stopping you taking that generic product and positioning and marketing it to specific verticals.
My home page, for instance, will describe the generic product, but quickly drive them off to an area of the site that focuses in on how the product applies to and delivers benefit to their specific industry.
Take a look at StackExchange: they have http://stackoverflow.com for customers, http://serverfault.com for system administrators, http://superuser.com for end-users and onstartups.com for businessmen. That can give an idea ;-)