Available four chars domains:

As usual, all of them were available at time of posting.

.com ( 8 domains):

X3IT.COM
UAU2.COM
W77L.COM
VS26.COM
VOI2.COM
VH1A.COM
VE8E.COM
VE1A.COM

.net (20 domains):

XQWH.NET
YPEN.NET
XPGM.NET
XHHL.NET
XFAM.NET
X3IT.NET
X3ID.NET
X00H.NET
WUUH.NET
WPTX.NET
WL7B.NET
WII5.NET
WHSJ.NET
W3W1.NET
W-WW.NET
UPVI.NET
UKLD.NET
UERF.NET
UCEG.NET
TYXW.NET

.org (1 domain):

WKTD.ORG