Suggestions for Improvement

I am a relatively average player, and, while I know how the pieces work, I am hoping to start basic/intermediate tactics.  Do any chess.com-ers have any suggestions for me as to books, software, and websites that can help me improve in this area?

The book suggested above is fine.It might be a suitable second book on tactics.

You should try the Chess Mentor demo on this site.

practice & chess mentor...

Recommend Practice.

Assuming you know all the basic tactical motifs (pins, forks, skewers...etc) I would suggest doing buttloads of tactics at http://chess.emrald.net/

Maybe do some endgame study too, The Karsten Mueller endgame DVDs from chessbase are really nice. :)