...using just an ordinary deck with no gaffs or gimmicks? I'm more interested in less well known effects, as opposed to classics like Triumph, ACR, et al.
At present, I am perfecting my handling of Japanese Aces, which I have almost got down. It's not really a devastating trick, but it's been a favourite of mine for some time now; I guess it's almost like a mini Oil and Water effect, which I am very fond of. I think it takes some degree of skill to perform it well and fluidly. I'm almost there!
There are some great gaffed card tricks/packet tricks out there (seems like I own most of them!), but there's nothing like showing a few tricks with an unprepared deck and pure sleight of hand. Spectators can, if they so wish, examine the cards to their heart's content. Can't beat it.

By they way, if anyone can suggest other Oil and Water effects for me to try - remember, no gaffs! - I would be grateful. Many thanks.