Intrinsic properties are
properties of an object that could
exist in the object even if it were
the only thing in the universe.
Mass, for example, is an intrinsic property. An object's mass does not change based on what is sitting next to it, or who is looking at it. Other intrinsic properties may include, depending on your exact definitions, things like complexity, roundness (an intrinsic property of circles), evil (the devil) and goodness (God), and existence (me). In some cases, it may also include things like 'value', for example, a human life may be said to have intrinsic value, apart from whatever extrinsic value it may also produce.
Weight, on the other hand, is an extrinsic property -- weight needs gravity, and does depend on what is sitting next to it (e.g. the moon or the Earth or the sun).