The altars I'm talking about are side tables, dressers, window shelves, anyplace where a soothing decor can be maintained. The purpose of such an altar would be to remind one of Spirit, to give something calm to look at when things start getting rough, a place to go for a quick and quiet moment of meditation before facing the day or conflict.
Outside of my ritual room, my favorite altar is in the large living room window. An old Singer sewing machine, closed cabinet, with two pieces of the beaten tinware I collect, a recently-repotted Pointsetta, a crystal bell, a candle-holder, and a ceramic cat grouped against the backdrop of a pale green sheer curtain with the sun pouring in behind it all. No matter what clutter is in the rest of the room, this little space is an oasis to the eye and a balm to the spirit.
Altars aren't specific to Pagans, either. My Christian mother has had her breakfast table altar as long as I can remember. A little box with cards containing uplifting scripture sits against the wall on a crocheted circlet and every morning, she takes one card and reads it, then meditates on what it says. The terminology may not be Christian, but this act grounds and centers her for the day and keeps her mind on 'Things of the Lord'. She has told me that there were many times the morning scripture would come back to her during the day to give her strength, or to re-inforce something that had happened.
Life can be hectic at times and it's easy to lose this connection with the Divine in our lives. An altar space doesn't need to be elaborate, just a few little things grouped together to remind us as we pass through the room that our Deity is with us and watching over us.