If you're traveling around a Spanish or English speaking country and you need translations between those languages, one option is a mobile application like Enterpreter: English to/from Spanish Talking Translator, Dictionary, Thesaurus.
As the title suggests, it offers a range of Spanish/English interpretation tools like a dictionary and talking translator. Once you've registered for an account, you're presented with a clear interface that allows you to enter sentences for translation, a dictionary, thesaurus and verb conjugator. With all these tools, you have the option of downloading, saving and listening to the results. With single words the results are good, but with sentences the intonation is a little odd, but is good enough to get by with.
There is a lesson of the day option, which will call up a different word and phrase everyday to learn. All of the translation is done online, so you need a data package to use Enterpreter a lot. Due to the cumbersome nature of typing, it's not very useful for language you hear: to translate a Spanish sentence to English, for example, you have to get the spelling and punctuation correct for the translation to work. For copying written text, however, it's fine.
Enterpreter: English to/from Spanish Talking Translator, Dictionary, Thesaurus isn't incredibly easy to use, but it does a reasonable job of translating words and sentences.