Another tactic you could try is to duplicate your data set, but to emphasize
the most current data you will duplicate each of those points "n" times more
than the oldest data. For example, say you have data like:
Date Value
---------------------------------
1-1-2010 $5,000
2-1-2010 $10,000
3-1-2010 $15,000
4-1-2010 $20,000
and so on. If you want to "weight" the most recent data, you could create
new data that look like this:
Date Value
---------------------------------
1-1-2010 $5,000
2-1-2010 $10,000
3-1-2010 $15,000
3-1-2010 $15,000
4-1-2010 $20,000
4-1-2010 $20,000
4-1-2010 $20,000
4-1-2010 $20,000
By duplicating the last points more than the first, you will "weight" the
trend line to be closer to the most recent data.
HTH,
Eric