The EVE spreadsheet continued to grow last year and now has graphs. This one measures the progress of my manufacturing corporation Trikassi Enterprises. Spotting bad trends that can be corrected has been a considerable help, overstocking (the orange line) for example.
The dark green line is the book value of the corporation, currently about $1,500 in RL money though unlike Second Life I can't cash it in. The Corp does pay for the game subscription, $30/month for my two accounts.