My 3 favorites right now are:

• Night Stalker (following sQreen's build)
  • Abilities
    • At lvl 6: 3-1-1-1
    • At lvl 11: 4-1-4-2
  • Items
    • Starting: Boots, Tangos, Clarity
    • Early: Phase Boots, Magic Stick, TPs, Smokes
    • Core: Aghanim's
    • Luxury/Situational: Gem, Vlads, AC, Halberd, Sheep Stick, Abyssal, Necro
• Zeus
  • Abilities
    • At lvl 6: 1-3-1-1
      
      • (however, you need to tweak it based on the lane -- often more Chain Lightning is better for more damage on a low cooldown and low cost)
    • At 11: 3-4-2-2
      • (again, might need to tweak based on circumstances)
  • Items
    • Starting: Tangos, Wards/Cour, several Clarity, and w/e else you want/need
    • Early: Boots + Ring of Basi
    • Core: Tranquils, Soul Ring, Magic Stick
      • Note: Break the Basi into comonents to make Tranquils + Soul Ring
    • Luxury/Situational: Force Staff, Eul's, Ghost Scepter, Bloodstone, Blink Dagger, Necrobook, Sheep Stick, Arcanes, Veil of Discord, etc..
• Nature's Prophet
  • Abilities -- standard
  • Items
    • Starting: Either Boots + Tangos + Clarity, or Tango + Multiple Clarity + Wards/Cour
    • Early: Phase Boots
    • Core: Mek
    • Luxury/Situational: Blink/Shadow Blade, Mjollnir, Orchid, Dagon, Sheep Stick, Necrobook, Deso, etc...
  • Notes: I do this when I get stuck jungling as NP. Jungling isn't very fast, so you need good map awareness and early phase to help with kills.

I also used to do Spirit Breaker a lot, which is pretty fun. I used the Goblak build:

• Abilities:
  • At lvl 6: 3-1-1-1
  • At lvl 11: 4-1-4-2
• Items:
  • Starting: you can do a lot. You can help with wards, or you can start with Boots. You can start with some +3 STR items, Stout Shield, etc..
  • Early: Boots, Urn, Magic Stick
  • Core: Treads, Blade Mail
  • Luxury/Situational: Vlads, Halberd, BKB, etc.

Tusk is another fun hero for support.

• Abilities:
  • At lvl 6: 1-3-1-1
  • At lvl 11: 4-4-2-1 (i.e. don't go past 1 lvl in your ult until your other 3 spells are maxed)
• Items:
  • Early: Boots, Urn/Medallion, Magic Stick
  • Core: Arcanes, Blink Dagger
  • Situational/Luxury: Gem, Halberd, Vlads, etc..

Someone else mentioned Kunkka (who you basically just skip Tidebringer on), and Morph (for the 4 sec stun). They are also both fun.