Toddlers learn best through engaging sounds and sights when learning all about language and various cultures. This is true whether you would like to teach a child to sign, recite the French alphabet, or sing in Spanish. They really do well to learn songs and poems in the languages you would like to teach them, because through repeated reinforcement through song or verse, they are more likely to remember what they learn.
Baby Einstein videos do a wonderful job of introducing children to concepts in recognizable scenarios that they are first able to understand in every life. I have personal experience with this brand, as I owned several of their videos for my daughter, who is now in a gifted and talented program in school, with an avid love of music, visual arts, literature, and a fascination with anime, Chinese and other Asian cultures, and phrases in different languages.
Recommended videos include:
My First Signs
Language Nursery (with songs and poetry from different cultures)
First Words Around the House
I would absolutely encourage the use of those videos no matter what a child's first-language is.
Another effective medium is flash cards to reinforce the words you are trying to teach. You can buy flashcards to go along with the Baby Einstein videos if you choose.
I highly recommend Baby Einstein Language Discovery Cards. They capture attention, and enable children to associate pictures with their written words in English, Spanish, French, German, Hebrew, Japanese, and Russian.
There are also many educational multi-cultural television programs available for toddlers and young children, such as Nickelodeon's Dora the Explorer for girls, Go Diego! Go! for boys, or Ni Hao, Kai-Lan for both genders. The most prevalent languages introduced to children today remain as Spanish, Chinese, Japanese, and French, with a growing minority in German and Russian. Having television shows, activities, and toys to help reinforce language awareness provide interactive learning from visual, audio, and haptic standpoints.
Speaking of toys, there are a few educational brands who have foreign language products on the market. They include:
GeoSafari Smart Talk Card Sets 1 (and 2)
Biligual Child's Lap Top (see also recommended products featured on the page)
Usbourne Books - collection of various language reference guides