Displaying geo data on openlayers
try http://drupal.org/project/views_geojson 

with the latest version of views_geojson and openlayers you can define a view (of type geojson) that accepts a bounding box as a parameter. 

With openlayers you can set the layer to use a bbox strategy so when you drag the map around it will send the bbox coords to the geojson view and just return points within that area.

I am new to Drupal and Im not going to lie this was a bit of a bastard to setup because there is not much documentation. I couldn't get the bbox contextual filter to work so I setup a custom filter that used top,bottom,left,right then wrote a rewrite rule in an .htaccess file that split the default parameter passed from the openlayers front end (a GET variable like BBOX=42,124,43,125) into the four filter parameters. This will NOT work if you expect your map to cross the equator or 0 meridian. But it works for me and I still hope to get contextual filters working at somepoint.