Most of this items/skills can only be used to get temporary vision of small areas,nothing really should extend the default day/night vision of your hero.
Only heroes/items currently in dota 2 are listed.
Invisibility, omnislash, infest and other spells that only displace/change the position of your hero's vision are not included,on the other hand gaining access to inaccessible high ground is included since it prolongs your vision radius significantly and makes ambushes easier even tho you can move.
Beastmaster boar and hawk companions can be used as scouts. The hawk can turn invisible at level 3 and be used as a ward fairly effectively, especially since it has flying vision.
Invoker
Tornado vision along the path.
Defeating blast vision along the path.
Sun strike reveals the area it will hit before the damage impact.
Clockwerk Rocket Flare gives you vision during the path + few seconds on the area they explode. If timed correctly, rocket flare can block creep camps.
Slardar Amplify Damage gives you vision around the target enemy and provides truesight of the enemies it is on (Not in AoE).
Lich Chain Frost gives you vision as it bounces from targets.
Dazzle Weave prolongs vision towards affected targets. Also provides 800 radius flying vision of the area it's on.
Spirit Breaker Small area around the charged enemy is revealed and the map you charge over is revealed during the charge. The target remains targeted, even if invisible, and a silhouette is visible. However, the target is not selectable without some other form of truesight.
Crystal maiden Frost nova reveals AoE at target area (due to short cast range only portion of it is useful).
Lycanthrope Your invisible wolves are very good scouting units.
Jakiro
Vengeful Spirit Wave of terror reveals area in targeted direction.
Anti-Mage access inaccessible high ground with blink.
Weaver Swarm grants vision along path, reveals the high ground also. If a bug attaches to a unit, vision is granted in a small area around the bug until either it or the unit it's attached to dies.
Morphling scouting with mirrored unit (Replicate).
Spectre
Haunt creates illusions around all enemies granting you short 5 points of view.
Spectral dagger reveals area along path, can get you to inaccessible high ground.
Mirana Sacred Arrow reveals terrain on its path.
Witch doctor area around Death Ward is revealed, due the cast range only small part of vision is useful.
Windranger Powershot reveals area along the path.
Kunkka
Bloodseeker Thirst gets you vision around enemies with low HP (if inside the required radius of you determined by thirst).
Broodmother your webs reveal terrain where they are placed.
Queen of Pain access inaccessible high ground with blink.
Pugna small area where nether ward is placed.
Bounty hunter Track reveals area around targeted enemy and reveals invisibility of units it is on.
Lone druid use bear as scout.
Storm spirit
Tiny tossing friendly units gets you higher ground vision.
Razor
Zeus
Lightning Bolt reveals small area around the target, revealed area gets truesight.
Thundergod's Wrath reveals all enemies on the map and small area with them for a second(hits invisible units and reveals them for the period).
Puck the Illusory Orb reveals terrain on its path
Chen persuaded units can be used as scouts.
Enigma Eidolons as scouts.
Shadow Shaman Serpent Wards reveal area around them.
Enchantress can tame units for scouts.
Dark seer Wall of Replica creates illusions that can be controlled as scouts.
Warlock vision around summoned Golems.
Shadow demon 2 controllable illusions and shadow poison, which gives vision of where it travels (goes over the high ground)
Venomancer plague wards grant you vision where they are placed(useful if placed on high ground).
Batrider
Ancient Apparition
Nature's Prophet can use his summoned treants as scouts.
Keeper of the Light Illuminate provides flying vision ahead of the keeper, with the range extending outwards as he channels.
Best Answer
According to http://dota2.gamepedia.com/Doom the important disabled passives to know are the following:
A full list of skills and items that are disabled is available on the playdota forum, this is not an official list however and future patches may change it.