I've seen a lot of 91.195.10.0/23 in recent days, a range of addresses belonging to
UkrStar ISP in the Ukraine. It's a sparsely occupied block, but there appear to be no legitimate sites here and blocking the whole lot could save you some grief.
A list of domains and IP addresses can be found at the end of the post. The WHOIS details for the block as as follows:
inetnum: 91.195.10.0 - 91.195.11.255
netname: UKRSTAR-NET
descr: UkrStar ISP
descr: www.ukrstar.com
country: UA
org: ORG-UA98-RIPE
admin-c: SER50-RIPE
tech-c: WIRE88-RIPE
status: ASSIGNED PI
mnt-by: RIPE-NCC-END-MNT
mnt-lower: RIPE-NCC-END-MNT
mnt-by: UKRNIC-MNT
mnt-routes: UKRNIC-MNT
mnt-domains: UKRNIC-MNT
source: RIPE #Filtered
organisation: ORG-UA98-RIPE
org-name: UkrStar
org-type: OTHER
descr: www.ukrstar.com
address: Dal'nitskaya 46, room 404
address: Odessa 65005
address: Ukraine
phone: +380482390190
fax-no: +380482324245
e-mail: noc@ukrstar.com
admin-c: SER50-RIPE
tech-c: WIRE88-RIPE
mnt-ref: GLOBALNETWORKS-MNT
mnt-by: GLOBALNETWORKS-MNT
source: RIPE #Filtered
person: Sanin Sergey Victorovich
address: Deribasovskaya str., 12
address: Odessa 65027
address: Ukraine
phone: +380487771551
e-mail: ser-0@clan-0.com
nic-hdl: SER50-RIPE
mnt-by: GLOBALNETWORKS-MNT
source: RIPE #Filtered
person: Grigoretskiy Sergey Aalexandrovich
org: ORG-UA98-RIPE
address: Dal'nitskaya str., 46, room 404
address: Odessa 65005
address: Ukraine
phone: +380482390190
e-mail: sg@ukrstar.com
nic-hdl: WIRE88-RIPE
mnt-by: GLOBALNETWORKS-MNT
source: RIPE #Filtered
route: 91.195.10.0/23
descr: UKRNIC-IP-BLOCK
origin: AS43479
mnt-by: UKRNIC-MNT
source: RIPE #Filtered
91.195.11.35
ns-free.org
ofpics.com
91.195.11.37
vocporn6.ru
videoxcx-onlina5g.ru
91.195.11.38
pornoxxx-onlina1a.ru
pornoxnx-onlinee1a.ru
porkaxnx-freex1a.ru
pornoxxx-onlinee4a.ru
porkaxcx-onlina2c.ru
pornoxcx-freex4c.ru
pornoxnx-onlina1e.ru
pornoxxx-conline3e.ru
pornoxcx-onlinee4g.ru
porkaxxx-conline3h.ru
91.195.11.39
minimart20.com
biggerthanvoland.com
boysandgirlsforever.com
whatwasinyourheart.com
91.195.11.41
yaxexzg.1dumb.com
costumeuniformporn.net
prettylatinatube.com
schoolgirluniformpics.net
skyinfo.in
streamretro.in
xoticpc.biz
91.195.11.42
curedret.ru
wrghghkfwerhdfghqwhtq.c0m.li
srvads.c0m.li
aangfan.in
floreli.info
certerpen.info
ageoloft.info
zndemstrnctwznskdsw-tsmcyuwaxldenctypzmb.ru
gdhordvl653hklyg.biz
wonderfulwriggle.com