List of servers:

NPLB LLRnet server #1:
maintained by Carlos Eduardo
server = "crus.dynip.telepac.pt"
port = 100
current range: 401 <= k <= 1001, n = ~ 299.7k (upto 305k ~60,600 pairs)

NPLB LLRnet server #2:
maintained by Carlos Eduardo
server = "crus.dynip.telepac.pt"
port = 300
current range: 401 <= k <= 1001, n = ~ 373.3k (upto 392.0k)

NPLB LLRnet server #3:
maintained by IronBits
server = "llrnet.no-ip.info" NEW: llrnet.ironbits.net from 10.03.2008 6:00-7:00 GMT
port = 500
current range: 401 <= k <= 1001, n = ~ 314.1k (upto 315k ~10,000 pairs; 305k-310k ~57,000 pairs)

NPLB LLRnet server #4:
maintained by IronBits
server = "llrnet.no-ip.info" NEW: llrnet.ironbits.net from 10.03.2008 6:00-7:00 GMT
port = 5000
current range: 301 <= k <= 399, n = ~ 370.4k

NPLB LLRnet server #5:
maintained by Adam Sutton (AES)
server = "nplb.rieselprime.org"
port = 300
current range: 401 <= k <= 1001, n = ~ 395.6k

Updated list here.