On the N900, if you just want a scrolling map, then mappero, ovi-maps, navit, pretty much any of them. Navit is the only one of these that will give you useful turn by turn navigation, but it's tricky to set up.

I would suggest you bring along a symbian phone with you. Not trolling, just that the N900 isn't that great for GPS in the Philippines. Yet.

Any Symbian phone with Ovi-Maps if you want functional turn by turn navigation, better if you can combine it with something like Garmin Mobile XT and the roadguide map (http://roadguide.ph/)

This will give you pretty good coverage of the national capital region, not bad coverage everywhere else.