250k - 500k a day, no level cap

This strategy can be very effective, but is only intended for the strong at heart. You will initially need a 75k investment as well as 42 days of patience. If you cannot provide these two things, then this strategy is not for you.

This strictly involves gardening, for those of you who have never gardened before, this will be a simple task. Most gardening requires you to be present throughout the week, watching your plants every move. Fortunately, this gardening tactic only requires you to check your plants once every "real-life" day.

First lets start with the initial 75k investment. You will need to spend this money on four Procelain Pots, four Tree Saplings, and one stack of Ice Crystals. Tree Saplings take the longest to grow, longer than any other of the plantable items, their growth time is clocked at 21 days. Once you have bought these items, place the pots in your mog house and plant your saplings. Please be sure to check your plants once a day just in case. On about the 7th day, your moogle will tell you that your plants aren't doing so well, so it is time to nourish them with a crystal, in hence, feed all of your plants one Ice Crystal. Then on about the 16th day, you will be required to feed your plants again, so feed them their second Ice Crystal. After 21 days, your plants will be ready to harvest, you can be sure of this if your plants are giving off a faint glow.

Why go through all this trouble you ask? Once you're ready to harvest, and you do harvest, you will obtain one Ice Ore for every plant you've planted. On my server, just one Ice Ore sells for 250k - 500k depending on demand. You can find it's going rate under Goldsmithing materials.

Now, don't be too hasty to buy all those wonderful things you've wanted for so long, that's not what the money is for. Notice above, I said 42 days, not 21. Now, with your new found mega gil, you want to buy 17 more Porcelain Pots, two stacks of Tree Saplings, and about four stacks of Ice Crystals. This totals about 400k - 500k depending on your server.

All you have to do now, is plant one Tree Sapling per day, while feeding crystals accordingly. After 21 days, you will begin harvesting one Ice Ore per day. Be sure to buy either another stack, or one Tree Sapling every day to plant a new one. Following this method will allow you 250k - 500k per day depending on sales at the auction house. On my server, Ice Ores are sold constantly to make Ice Staves.

If you can keep up with this formula, you should never have to farm again. If done correctly, your gil will be maxed out in six to eight months time, due to you making around 12,000,000 gil per month.

I hope this helps many, take care and God speed.