This site has an interesting set of categories of words you can learn including some critical phrases for the adult who has some knowledge but needs to fill in some vocabulary.  For example, there is a section on business terminology (like market size, revenue, etc.) and economics.

http://www.learn-hebrew.co.il/

The site is well done with a blox that lets you click on the word to hear its pronunciation and phoenetic as well as hebrew spellings are visible.  The author has done a variety of other interesting sites for English and Spanish too.  Its worth checking out in the About section.

Another one of his that is great is for Hebrew verbs: http://www.hebrew-verbs.co.il

What I love about the verb site is it conjugates the verb for you and also lets you hear the conjugated variations.