Sometimes it's desirable or necessary to add a wall to your front yard for either privacy, security, safety, or all of the above. If it's possible and fits into your budget, you may consider creating the wall from the same or similar material of your home. If not, then pre fab concrete blocks will work fine as they come in many different styles and color combinations. The directory at retaining wall ideas has a lot of pictures and examples of using retaining walls and pre-fab concrete blocks in designs.
Once created, retaining walls and planters like these offer a lot of opportunities for planting and accents.