What are the best Database Analytics Companies for analyzing several 1000s or Mio. of products,sum them together and analyze them for statistics?
I'm not sure how you would do this with a nosql database like mongodb but in a typical data warehouse I would do this with the dimension table hierarchy.

Product_ID   Full_Product_Nm            Product_Lvl1       Product_Lvl2
----------   ---------------            --------------     ------------
1            iPad 16GByte UMTS schwarz  iPad               iPad 16gb
2            iPad 16GB 3G black         iPad               iPad 16gb
3            iPad 64GByte UMTS schwarz  iPad               iPad 64gb
4            iPad 64GB 3G black         iPad               iPad 64gb


Then I could join my fact table to the dimension and pull out the hierarchy level that I would like to report on.  

So in your example I could pull out the Product_Lvl1 to get iPad but if I wanted to compare sales/inventory of 64gb compared to the 16gb iPad I could do that using the Product_Lvl2.