Underworld Connections 1BB
Enchantment - Aura R
Enchant Land
Enchanted Land has "

, Pay 1 life: Draw a card"
Initially, I dismissed this as a Phyrexian Arena that was vulnerable to Strip Mine, but then I realized untap effects let you re-use the ability. If you're able to draw 3+ cards a turn off this card, I think you're cooking with gas. So, what untap effects see play in Vintage?
Voltaic Key + Artifact Land with Connections = Sketchy and vulnerable to wasteland.
And... that's about it. Well, what untappers do NOT see play in Vintage, but are cheap enough that they might?
Arbor Elf - Bad card except in Elf Combo, and Elf Combo does not want this card.
Burst of Energy - Too narrow
Cloud of Faeries - Interesting. I've used this dork before in decks that need a free body.
Snap - Like Cloud, interesting. It's great against Blightsteel and it's free. Maybe you could find synergy here...
Deserted Temple - Very interesting. Could work in a mono-black deck with other powerful lands.
Dream's Grip - Better than Burst of Energy, but still bad.
Earthcraft - Possible in a squirrel combo deck, but not sure if its worth it for Connections. 2GBB = draw 2 cards a turn? Eh...
Emerald Charm - Better than Burst of Energy, used to actually see play in some decks. Probably still not good enough.
Ghostly Touch - A whole deck fulla 2-for-1s! Pass.
Lapis Lazuli Talisman (and friends) - Holy balls, a use for Talisman? Haha no, it's still too expensive. You could do worse than pay 3 to draw a card repeatedly, but as a 5 mana two card combo, this is bunk. HOWEVER if anyone makes a winning decklist actually using one of the Talismans, they will be my hero.
Magus of the Candelabra / Candelabra of Tawnos - Cheap and efficient, but what else is in your deck making use of these effects?
Orbo Breezecaller - Price seems too steep. I guess it's bonkers good with Fastbond in play, so maybe there is a deck to be made here.
Reset - Only goes in one deck. High Tide does not want Connections.
Reminwind Taskmage - THIS seems possible. Snow requirement is steep, but he works as a good Tinker foil as well as helping your draw engine.
Trickster Mage - Cheap and all, but there have to be better options. Turns the extra card you draw into a loot effect.
And thats about it. I guess I'd see myself trying to brew this with a deck featuring Snap and Cloud of Faeries, maybe some sort of strange BUG tempo deck. Beyond that, not seein' much utility for Vintage.
[EDIT] - Whoops, I'm not in the General Strategy subforum. Can a mod help me out here? Sorry.
Added
so people would no longer risk shitting themselves or accidentally buy this card.