Lin,
the Lightsphere is very popular among newer aspiring photographers and has the benefit of improving the quality of your light with very little effort or thought.
the biggest drawbacks are that it's very bulky and relatively expensive, which may or may not be issues for your shooting style and budget.
i use a modified version of
Peter Gregg's A Better Bounce Card, which can provide more directional light if you're willing to do a little thinking and adjusting while you're shooting.
the A Better Bounce Card is very inexpensive but can be a little bit of work to adjust.
there are many other products out there (Lumiquest has some great ones) but i'm a huge fan of the ABBC.
bill