I have to make a script similar to that on http://www.uship.com/.
I needs to save routes in a database and have a search engine that whe enterint the start and end zip code will show all the routes close to that entered.

I have no ideea how to do this and ii was hoping you guys could point me in the right direction.

Thank you for your ideas.

you don't know to take similar results, or what?
http://www.google.com/search?q=mysql+similar+results
or search at phpclasses something [there, sure, are some classes]

maybe my explinations were not clear. I will try again:
For example i input a route from Washington to New York. The results should return every shippings in the database that are along or close to that route ( meaning road from washington to new york ).

For example it should return a shipping from baltimore to wilmington because the route from Washington to New York passes trough them. Or a route from baltimore to Philadelphia ( here it should say how much miles/Km is of route ) since philadelphia is not on the search route but it is close to it.

Hope this makes thing clearer about my question.

I assume you have a database of these information to start with (geographical locations, road distances) but after that it's just a graph.

http://en.wikipedia.org/wiki/Graph_theory

And I think specifically what you're looking for

http://en.wikipedia.org/wiki/Shortest_path

Dijkstra is easy to implement:

http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm
PHP code here: http://en.giswiki.net/wiki/Dijkstra's_algorithm

that is the thing .... i don't have the database. I was wondering if anybody has a service for this that they would recommend. I was thinking google maps.
Also how do you suppose i should store the shippings in the database for fast calculations for the application i described above. I reckon start Zip and end Zip, would not be to correct.