Being a devoted father and husband, I don't spend as much time playing Eve as I once did. With only a few minutes here and there to spend playing, I finally started doing something I'd been keen to do for a while: playing the market.
In the past, I'd done the 'hauling' type of trading, where you buy your widget at place A, then transport it to place B, and sell it there for a profit. Eve's markets are broken up by region, and the secret to making money this way is getting market data across multiple regions, and then using a fsck-off big SQL query (that's a technical term) with some really ugly joins to identify profitable trades. It can be done - that's exactly what my market trading app did for me in '06 and early last year.
The down side is that you still need to invest time, collecting and hauling goods. You also need to to jump between regions to collect all the market data.
I finally plucked up the guts to do the 'trading' type of trading. With hauling, you're looking for existing buy orders which are higher than existing sell orders. What's a lot more common, is the converse. If you're willing to go out on a limb with some capital, then the greater the gap between buy orders and sell orders, the greater the opportunity for arbitrage.
I started out buying goods which were offered at well below the market's published average figures. Re-sell them at the market average, and eventually you'll make the sale, and a profit to boot. It didn't take long before I realised that instead of worrying about averages, all I needed was to find the margin (and volumes to ensure a quick turnaround). If the gap between buy and sell is high enough, you can afford to place attractive buy orders which'll get taken fairly quickly, and then flog your stuff at or below the market average, with a high probability of having your orders met before anyone else's.
I haven't made a mint, but it's fun making (imaginary) money doing (next to) nothing. Its a fun challenge (how much can I actually make), it's quite a kick going up against other traders who have the same idea (I've already prompted a mini-price war in one market), and it's a good way to build up dosh to buy the heavy artillery for when I have enough time to indulge in normal blow-shit-up online gaming.
Of course, the real mind-fsck with all of this, is that every item I buy and every item I sell, is happening with another character run by a real-life human being. I could never do it in the real world, but I'm participating in an online economy, and making a good profit doing it. It's insane.