Depending upon how interested you are, there are several home energy monitors on the market, some of which are DIY installs.
The Blueline Powercost Monitor is a definite DIY install (for the most common meter types). It is a little box which interfaces with the meter (even the analog style), and monitors the usage in real time. It integrates with Microsoft Hohm, and gives you real time statistics, recent usage history, fancy graphs, etc.
The other big contender is the TED 5000. This integrates with Google's competing service (PowerMeter). This is pretty much the same story (statistics, history, graphs, etc.). It is essentially an ammeter hooked up to the electric line coming in your house. Because of this, it is more accurate than the Blueline. The downside is that you have to open up the breaker box to install this (which may or may not be DIY for you).
Compared to the standalone ammeter (~$80), this is significantly more expensive (~$250). However, the usage statistics over time may help you to reduce your overall electric usage once you have found and eliminated the main hog(s) in your house.
More reading:
Engadget Review of the Blueline - With some comparisons to the TED5000.