I don't know if these are single use coupons or not but here are some I found, all dell mind you. I did not use any of these but as they were found on other public forums, some may have already been snatched up.

10%
0?87TJ8 3W7FSTZ
G2DL??? 04PPQ0Z
RWD55N KSCFDLT6
LW7KXX DDRQ91VV
KP21WR ZB511GV3
H70GKW ZT1H16SQ
L6SH6Z LG66$MBN

No luck on the 15% codes so far. They go like stink.
I put spaces in the 7 codes to eliminate google searches and web crawlers. Obviously remove the space before redeeming. Good luck everyone.