The benefits of owning a house may not be immediately evident. Although it is impossible to lock the door, no NPCs will enter your house when you are not there, nor will any NPCs steal items from your house. Once a home is purchased and has been entered, the door is permanently unlocked (although there is a glitch associated with the Bravil house). There is no limit to the number of houses you can own. However, only the houses purchased inside major cities count towards your 'Houses Owned' statistic.
Some of the official downloads also add new homes, and there are even a few free homes that become accessible after completing associated quests. Each major city (except Kvatch) has a house available for you to purchase.
Houses in Oblivion are buildings in which you may sleep and safely store items in non-respawning containers.
