How can I add more than one pointer to a map? I want to create a block which has search functionality for looking up locations. I want to be able to add a pointer to the map at the searched for location. 

It should be able to add more than one pointer to the map based on what is searched for. 

An example of pretty much exactly what I'm looking for the input of locations can be seen here:
http://www.mapcustomizer.com/

Does anybody know how to do this?

Thanks
You can use Get Location module for this functionality. It will create multiple location markers on a single map, with a popup bubble info and it comes up with inbuilt views. You just need to enable a block after installing it. Some more details about this module (from its project page):

... will provide Google maps API version 3 enabled maps on which to display markers of locations found in location-enabled content-types.
These can be displayed per node, eg &quot;/getlocations/node/xxx&quot; will display all the locations associated with that node. They can also be displayed per content-type, so if your content-type has a machine name 'venue' you can show them all with &quot;/getlocations/type/venue&quot; and it also supports paths like &quot;/getlocations/user/xxx&quot; and &quot;/getlocations/users&quot; for location-enabled users. These links have their own access permissions so control can be exercised on a per role basis.

If looking for custom thing, specify your complete requirement.