For reference, here are the raw draw spells I run in a monored deck:

Wheel of Fortune
Wheel of Fate
Illuminated Folio
Temporal Aperture (doubles as 'mana ramp' in the same way that Bloodbraid Elf was "cantrip+Black Lotus")
Mind's Eye
Dreamstone Hedron
Memory Jar
Crystal Ball
Thawing Glaciers

and there are plenty of other decent options I'm not running:
Urza's Blueprints is fine if you have enough mana, or are running various untappy things (Karn+Voltaic Construct is nice to use while echo is on the stack)
Candles of Leng
Kozilek, Butcher of Truth
Darksteel Pendant
Planar Portal
Tower of Fortunes

Cards that 'buy' me additional 'cards':
Kumano, Master Yamabushi
Valakut, the Molten Pinnacle
Flameblast Dragon
Hellkite Charger
Jiwari, the Earth Aflame
Obsidian Fireheart
Shard Phoenix
Viashino Heretic

Single-use cards that are scalable:
Comet Storm
Fault Line
Jaws of Stone
Molten Disaster
Shattering Spree
Spire Barrage

And last but not least, there’s Akroma, Angel of Fury, who is a good mana sink, and also playable at two different costs.

@QED2: I like how you pointed out the scalability of cards like Wolfbriar Elemental (or something like Comet Storm in mono-red). That is definitely important to opening up your options. Now if only red had Transmute…

I think the more we try to come up with synergistic answers to lack of cards/mana/options, the less we need fill up card slots with hard card draw engines.

Thanks for the ideas!

If you want to ensure a good flow of mana and cards, look for cards that are cheap but will be useful even late. Some example:

-equipment, especially the good card advantage ones like SOFI and SOLS
-cheap card drawing, like Harmonize
-utility lands. Urza's Factory comes to mind.
-cards that draw while doing/after doing other things. Everyone gets a Dreamstone Hedron; other colors have more specialized options.
-cantrips like Preordain, or anything that cantrips. You don't want Tormod's Crypt; you want Nihil Spellbomb, or Relic.
-cycling cards are generally pretty marginal, but the lands are generally fine, and there's others with a wide-enough application to be worthy of inclusion (Radiant's Judgment)
-a commander that can get your cardflow moving. Captain Sisay is one. Xira Airen is also.
-a commander you can replay effectively.
-scalable cards (think X spells). Wolfbriar Elemental is fine at 5-6 mana and great upwards.
-cheap tutors. all black decks can start with demonic, vampiric, diabolic, and beseech (and grim and imperial seal if you have money or proxies). specific decks can add Diabolic Intent, Buried Alive, or Dimir House Guard (->Diabolic if you're flooded or have Coffers going). You can also stretch for Shred Memory (transmutes for Demonic if nothing else) and Dimir Machinations (Phyrexian Arena).
-recursion effects: Mimic Vat, Erratic Portal
-just plain old card drawing: Mind's Eye, Temporal Aperture, Illuminated Folio. This is the richest nation of earth, there's enough of these out there that no one should ever have to use a Jayemdae Tome again.

Alternatively, just running more useful utility lands can help mitigate the problem of mana flood, since you'll have more lands that provide spell-like effects to make up for your lack of real spells.