§ realia: real objects are a very effective way of introducing some grammar items (eg comparatives and superlatives)
§ cuisenaire rods can be used in numerous ways (eg to represent form)
§ the classroom itself, the school building, and the immediate surroundings are rich in potential - for example, prepositions, passives, question forms, etc)
§ reading texts have the grammar stucture embedded in a context, which helps tremendously - almost all grammar patterns can be introduced from texts. The text needn't contain multiple examples of the structure: one really clear example is all you need.
§ songs may also be a source of grammar - but make sure that the words are clearly audible and distinguishable (The Beatles lyrics, for example, are really clear)
§ miming can be effective, especially at lower levels - miming the present continuous is relatively straightforward