Here's a list in recent years as per CapFriendly.
2016: NJD trades #11 to OTT for #12 and #80 (3rd round)
2012: BUF trades #21 and #42 (2nd round) to CGY for #14
2009: NYI trades #16, #77 (3rd round) and #182 (7th round) to MIN for #12
2008: NYI trades #5 to TOR for #7, #68 (3rd round), and #37 in 2009 (2nd round); NYI trades #7 to NSH for #9 and #40 (2nd round)
2007: STL trades #9 to SJS for #13, #44 (2nd round), and #87 in 2008 (3rd round)
2005: ATL trades #8 to SJS for #12, #49 (2nd round), and #207 (7th round); ATL trades #12 to NYR for #16, and #41 (2nd rounder)
Those are the examples post cap world of trades within the top 15 strictly involving draft picks. Not something that's really happened as much recently.
NHL Entry Draft Picks - CapFriendly - NHL Salary Caps