zandperl got lost on TV Tropes and decided to make a meme out of their
list of longest running webcomics, and I thought that was awesome so I'm totally doing it :D.
Italics if you're current on the series
Bold if you've been reading from the start (or close to)
Strike if you read it once but gave up
Underline if you want to read it or want to catch up with it, but haven't
Comment for anything else
18 years
Kevin & Kell. 1995-present (First webcomic I ever read, on the computer I bought with my Bat Mitzvah money ;P)
Slow Wave. 1995-present
17 years
Melonpool. 1996-present
Sabrina Online. 1996-present
Ubersoft. 1996-present
16 years
LCD: 1997-present
Nukees. 1997-present
PHD. 1997-present
Sluggy Freelance. 1997-present
User Friendly. 1997-present
15 years
Freefall. 1998-present
General Protection Fault. 1998-present
Jerkcity 1998-present
Penny Arcade. 1998-present (They were cool once. . .)
PvP. 1998-present (Maybe I'll pick this back up)
SSDD. 1998-present
14 years
Doctor Fun. 1993-2006
Argon Zark. 1995-2008
Goats. 1997-2010 (It's over? Maybe I'll go read the ones I've missed.)
Alex. 1999-present
Cat and Girl. 1999-present
College Roomies from Hell!!!. 1999-present
Funny Farm. 1999-present
Namir Deiter. 1999-present
Real Life Comics. 1999-present
Sheldon. 1999-present
Superosity. 1999-present
13 years
Polymer City Chronicles. 1995-2007
Chopping Block. 2000-present
Diesel Sweeties. 2000-present (no idea why I dropped this one)
Megatokyo. 2000-present (couldn't take the hiatuses)
Schlock Mercenary. 2000-present (Seriously seriously awesome)
Zortic. 2000-present
Little Gamers. 2000-present
Sacred Pie. 2000-present
12 years
Bruno. 1996-2007
Achewood. 2001-present
The Cyantian Chronicles. 2001-present
Captain SNES. 2001-present
The Devil's Panties. 2001-present (another one I've no idea why I dropped)
Drowtales. 2001-present
Faux Pas. 2001-present
The Perry Bible Fellowship. 2001-present
Phil Likes Tacos. 2001-present
Something Positive. 2001-present
Tru Life Adventures. 2001-present
Wapsi Square. 2001-present (Apparently I lost a bunch of my comic links at one point, and now I'm going to have to add them back in ;P)
11 years
Ozy And Millie. 1998-2008 (This was possibly the best webcomic ever)
Ctrl+Alt+Del. 2002-present
Dominic Deegan: Oracle for Hire. 2002-present
Errant Story. 2002-2012
El Goonish Shive. 2002-present
Irregular Webcomic!. 2002-presentnote
Legostar Galactica. 2002-present
Planet Zebeth. 2002-present
Saturday Morning Breakfast Cereal. 2002-present (I read it completely at random, which seems appropriate)
The Tao Of Geek. 2002-present
Unshelved. 2002-present
The Whiteboard. 2002-present
10 years
The Mansion of E. 2003-present.
Station V3. 2003-present.
Dinosaur Comics. 2003-present. (I also read this one at random)
Questionable Content. 2003-present.
Applegeeks. Started in 2003 and added a B Side Comic called Applegeeks Lite, updating faithfully three times a week, in April of 2006. Due to the main comic's Schedule Slip, the 1000th comic between the two was AG Lite 476, on 24 Jun 2009.
The Order of the Stick. 2003-present. (So glad he's back!)
Exterminatus Now. 2003-present.
Least I Could Do. 2003-present.