It is a commonly known fact that information is stored much faster and effectively in human brain if it helps achieving some goals. So, most part of the knowledge you were taught to in school usually disappears from memory as soon as you don't have to pass exams. The same is applied to learning languages.
Traditionally, a foreign language is considered as an object for investigation and analysis - for students. Of course, students know that the final goal of their analysis is the possession of the language they study. But their brains refuse to act in this way. Compare academical study of a foreign language with the study of native language by a child. The child is not taught to rules and grammar, neither is the laguage a goal or an object for investigation. Language is always only a tool to get something. So every one of us speaks native language perfectly - not because we learnt our native language in school!
Implicit ways of learning languages try to implement this idea. In these methods, a language is never considered as a goal - only as a tool to know something (usually interesting).
The simplest realization of implicit learning is parallel reading.
In parallel reading the student first reads a sentence in his native language, say English:
A car is going quickly.
... and then the translation of this sentence to the language he is studying, say Lojban:
le karce cu sutra klama
By reading thousands of sentence pairs, human brain automatically, implicitly grasps understanding of all internal regularities of the language, absolutely without any efforts from the student to memorize anything (exactly as a child learning his native language). Imagine that these sentences form an love story or a detective story - and this method becomes not only simple and effective, but also very amusing.
A program for parallel reading text is available on this site. Open Parallel 2 for details and download.