web based contact management

Google is your friend,
http://sourceforge.net/projects/php-addressbook/
http://webscripts.softpedia.com/script/Organizers/PHP-Address-Book-31592.html
http://php.about.com/od/finishedphp1/ss/address_book.htm
etc.

Haven't used any myself so can't give a personal recommendation.

 

If those links don't get ya what ya need, next focus on contact management tools related to CRM (Customer Relations Management). There are an abundant amount of CRM tools out there to offer solutions for sales and contact management. I work with the government, many agencies deal with this kind of thing often enough.

Here is a page for CRM shareware solutions

Here is a page that allows you to specify your needs and it recommends professional CRM solutions merely so you can compare what you lose in open source or shareware tools.

The best web based CRM solution I've seen is Sales Force. I would not call it small, though, but they have competitive pricing and one heck of a support and development community. Consider this as the company grows, not now.

-jim

 

highrise

You should check out 37 signals Highrise CRM. I use it and love it.

I think the free version only allows two separate user accounts though. But I think the price for an account is fair.

 

Hi gonnabuyamac. I can recommend Overture http://overturehq.com A friend uses them for his booking agency and has only positive things to say about the program (you could contact him if you want feedback: http://www.functioncentral.co.uk). It's web based, I don't know if you were looking for something simpler. Hope this helps...