Below is a list of sites where you can get POI lists.
Loading the POI onto Garmin units is easy with their POI loader.
All you need is a PC or a Mac and their free POI Loader software
Got a TomTom? No problem, you can check TomTom's website for a lot of information on making your own POI collection or installing others.
Garmin has a list of POI suppliers .
TomTom maintains a similar list for TomTom POI collections
POI Factory - a broad collection of POI files that can be uploaded and shared. Free and many quite up to date.
GPSPassion has an extensive list of free POI lists at their site available for download and collaboration on.
GPS Waypoints is another member supported sharing forum with quite a few collections including a lot of international POI.
TomTom-ers shouldn't feel left out, as PocketGPSWorld has a database that's TomTom compatible.
This site is interesting for those of you who want to get into the POI creation game: POI Editor , a slick website that helps you make your own collections and can save that collection in several formats including Garmin, TomTom and Mio.