This has been done in various ways with Luna, Medusa, Tinker, and Drow. The problem is that it's super easy to shut down and not inconspicuous at all.

Heroes who can jungle reasonably well (that dota2wiki link is pretty bad):

- Axe
- Batrider
- Chen
- Doom
- Dark Seer
- Enchantress
- Enigma
- Lifestealer
- Lone Druid
- Lycanthrope
- Nature's Prophet
- Ursa

Heroes who can jungle if absolutely needed but probably shouldn't (in addition to those mentioned at the top):

- Bloodseeker
- Skeleton King
- Huskar
- Phantom Lancer