we are a bilingual english/spanish family and i have tried to find stuff for dd that is in spanish toy, video and book wise. we speak mostly spanish at home and english in the outside world so i want her to be exposed to both when reading, etc.
leap frog has some toys usually found online that are spanish speaking.
we have the brainy baby spanish video and she likes that. it teaches colors, numbers, some verbs, some nouns and a few manners.
i think most important would be exposing your son to the sounds by way of music, etc. we found a cd at walmart called beary la bamba and she loves it. i don't mind it either. i have heard good things about jose luis orozco's stuff too. de colores in particular.
another idea if you plan on letting your son watch movies is to get DVDs with spanish language tracks.
pm me if you want any other suggestions!
also, if you happen to have a spanish channel like univision, i think they have plaza sesamo (sesame street) early in the morning.
also check out this website www.spanishtoys.com