Custom ignore files, for one. I don't need it to sync .git, .swp, etc. It's an amazing service as-is, but it can be better (for power users, anyway).

I would love to be able to leave some folders in the cloud on some machines. My laptop has a small hdd... Overall I love Dropbox, but I am confident it can and will improve.

Create a second account just for the laptop and set up a shared folder between the two accounts. Put all the files you want on the laptop in the shared folder.

That kind of scheme unfortunately takes most of the ease of painless syncing away...

Good idea. Not sure I can stay under the free limit or want to pay for a second account, but if I can that will do it.

The one thing I want is to be able to turn certain folders off/on depending on the machine.

This is the only feature at the moment that i need which dropbox is lacking. Makes it difficult to use Dropbox in more than one environment such as work versus school when everything is synced everywhere.

I agree - it also syncs certain files I don't want synced - like log files.

yes! .dropboxignore please!

Maybe make it so certain clients don't take up the entirety of your CPU while they try to add bits onto the icons of the files themselves...

Been using Dropbox since beta. Never had this problem (XP and Vista 32-bit).