I think a spawn tracker wouldn't work since with some experimentation, people would quickly figure out when to move to another spawn, and scripters would have it down to a science within a week. It also punishes legitimate hunting. There are days where I feel like killing Miasma, so I grab my paladin and kill Miasma. There are days I feel like fishing up SOS, so I do that. I tend to stick with one thing since there is less switching of equipment or characters. Farming the same monster again and again is one of those lazy things we do. I may switch up what I kill (haven't killed Terathan avengers in a year or so, Balrons since Treasures of Tokuno, regular demons since Magincia), but I tend to pick a target for a particular fighting session.
Also, if you are walking through a dungeon, they tend to have the same things. Fan dancer dojo is mostly fan dancers with a few other tasty bits. Despise is ogre lords and the stuff you fight while you wait. Hythloth is demons, demons, and bigger demons.
Gold sinks are hard to make. I have never bought expensive hair dye from the hairstylist NPC. I got my taxidermy trophies from a friend. I may have 15 boats for RP reasons, but they are cheap by today's standards. I have my fill of houses unless they let us have more. Training characters gets cheaper and cheaper.
Insurance is the last really good gold sink. Before insurance, we all used crafted exceptional armor, so resources got burned through making that, but insurance still costs more on average I would suspect.
One change that would work but would cause a lot of complaining is making armor repairs more expensive (burning up resources or gold). I know some games already do that, but these games also don't have insurance since characters keep things on death I think.
New items and decorations aren't terribly good goldsinks. They are either one shot goldsinks (buy them once and you are done), or they require expensive upkeep and no one gets them. What decoration would be cool enough that you'd spend a million to look at it for a month? What piece of clothing? I could see people spending uber money for temporary powerful items, but these have the drawback that they would be unbalancing. For example:
Glass Sword
1 Use
Instantly kills any creature or player on a successful hit
Use Best Weapon skill
Depending the the price it would either be broken or totally useless except in certain situations (player revenge).
New areas like the Nujel'm dungeon that require entry fees could be neat gold sinks, if they had more things to do. Special NPC guilds like the old days with neat perks that cost a great deal to be part of could be another neat gold sink. Heck NPC guilds could be the gold sink faction-like organizations of Trammel, controlling towns through PvM, trade, crafting, and general gold-sinking.