Hide small speakers in and among other small decorative items in the room. Don't perch a speaker on a tabletop as if on display. Look for items in the same color family if possible so speakers blend into the décor. Or place speakers in the back of a grouping essentially the same height as the speakers.
Shelve the problem by placing small speakers on a shelf surrounded by an interesting array of books or green foliage. Shelves can become virtually invisble with the right surroundings. Turn speakers on their end to squeeze into small spaces as well as blend with the general shape as other object on the shelf such as books placed horizontally rather than vertically.
Paint speakers to match decor if they really stand out in the room. Speakers often come in a hard plastic that may be paintable with paint especially made for plastic. Take care not to spray the mesh covering over the speaker with paint as this may impede the sound quality. Painted speakers can be placed inconspicuously beside a couch or chair.
Hide tall speakers among floor-standing vases of the same height or behind large floor plants. Speakers have improved upon their design so that even when standing alone most high-end speakers have clean lines and modern sensibilities. However, even a tall speaker seems out of place in certain room décor no matter how nice its form. Look for something tall to group them with or hide them behind.
Hide speakers where no one would guess a speaker is being hidden. Audiovox makes more than 20 covers for wall-mounted, tabletop, floor-standing and trunk-style speakers. Speakers get disguised as mantel clocks, candle holders, faux books, planters, wall sconces, vases and floor-standing baskets. For those into serious music, big subwoofers in a room get disguised as trunks.