POIs? Not very exciting, but for example, Decathlon (France) have a downloadable file on their website of all their store locations in Europe (excluding the UK ones, strangely). This can be placed on the SD card and the stores can then be accessed in the Find menu - and they will show on the map in normal use if the zoom is close enough.
Using a POI Editor you can merge several datasets and assign various symbols - so I have a single POI file including all Decathlons, all Intersport, all Sport 2000 and lots of French LBS - so I can always do a find on 'nearest bike shop'. Strangely, my combined file also includes all real-ale pubs in York. It's easy in the GPS Find menu to filter the search to any one of these categories, so you can combine anything (because, like the map, you can only have one active POI file).
All that said, it's sat on my GPS for 2 years and I haven't really found a use for it (nearby Decathlons tend to make their presence rather obvious anyway!).