If you're specifically interested in perks, there's also an "ARPA" program you can join which includes additional alternative payment options and features beyond what basic validation provides:

Did you know you can become a permanent LIFETIME member of SDF
by making a onetime donation of $36?

ARPA members have immediate access to:

 600mb total / 20000 files in four areas
 access to multiple subdomains                              (mkhomepg -a)
 voting priviledges on new system features                  (vote)
 telnet, ssh, ytalk, irc, irssi (non-proxy)
 wget, snarf, ftp, scp
 gcc, perl, php, python, ruby, et cetera 
 Mail and USENET news via UUCP 
 SDF VoIP Basic Telephony Service
 (type 'software arpa' for a complete list of programs)
 access to join VHOST, DNS, VPM, DBA, TWEAK & MetaARPA membership levels

You too can become a LIFETIME member of the ARPA group by sending a
ONE TIME contribution of $36 (or more!) to SDF.  NON-US Residents can join
ARPA by sending the amount via International Money Order, cash (US/EURO) or
by PAYPAL.  Be sure to include your user id of 'SDF UNIX USERNAME'

  LAND                       INTERNET (donations of $3.00 or more)
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|  SDF Public Access UNIX  |  PAYPAL.COM:   paypal@freeshell.org  |
|  PO BOX 17355            |                                      | 
|  SEATTLE WA 98127 USA    |  (Be sure to include your user id)   |
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|  Donations or dues via crypto: E-mail 'membership' for options  |
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Acceptable funds:  Western Union, Cheques, Money Orders, US, CDN, EURO, UK, YEN