US Dollar x Mexican Peso
Android version, Coverts from USD to MXN and back. Widget to have instant exchange rates visable.

Convert to Metrics:
Unit Converter from Google Play Store
Convert length and distance, speeds, volume and weight, temperature
From Browser:
Language Translator:
Google Translate from Google Play Store
Free translation from any android device or your desktop
From Browser:
Language Lessons:
Browser based:
Language Zen – has free lessons for primary levels. Only $35 USD for 3 months for premium version. Focus is on Latin American Spanish, Android version on Google Play Store
Duolingo – free and premium lessons,
Android version on Google Play Store
Babbel – Babbel is different in that it teams you up with native language speakers to help you learn. But it has no free version. Cost is as low as 6.95 per month. Android version on Google Play Store
Communication apps.
Facebook on Google Play Store
WhatsApp on Google Play Store