My favorite Adobe Elements(all photoshops have this feature) feature is the transform feature.  It straightens your vertical or horizontal lines so they are parallel with the frame of the photo.  The wider the angle the lens the more chance you have for perspective distortion.  I shoot most interior photos at 10mm to 14mm and no matter what you get those vertical lines out of wack.  I run all my photos through Adobe before posting.

This photo was taken off my Multiple Listing Service.  I found it to be a good example of a correction with the transform feature.  I find that pictures falling over tend to be very distracting and can send a subliminal message to your veiwers.   When I see this photo I just want to prevent the items frm falling off the mantle. The transform feature takes a minute to run and last time I looked adobe elements was $99.00.  A must have I think for the listing agent.

I happen to use Adobe Elements 5.0 but all versions of photoshop have this useful feature.  Just bring your photo into Elements.  Click on the Image button, go to Transform and choose Skew.

Got to view and turn on the grid to aid you in getting vertical lines.  Drag the necessary corner points until you get vertical lines that are parrellel to the frames or to what might look natural.  With this photo some horizontal lines needed to be corrected also.  This isnt perfect but a lot better than the original picture.  Trying to get the photo right when you are taking it is a better choice.  But, this is not a bad alternative especially for minor corrections.

Crop your photo and then save!!

Before

After

Another Sample

Hope this was helpful.  Good Luck!!