for me, it was watching both discs of the first season of entourage in one sitting. i blind bought both seasons at target the week season 2 came out. I was only planning on watching maybe 2 episodes, but just kept watching and watching and watching. I finished at maybe 1:15 am. the show is so brilliant at taking shots at hollywood. it also feels real, and not a fake version of hollywood. Not to create a pun, but Jeremy Piven as Ari Gold is well gold. Even though he doesn't have alot of screen time per episode, he makes the most of it, and i wouldn't be surprised if half of his stuff iimproviesed.
can't wait to get into season 2 sometime this week, so i can finally dive into season 3.

Ari gets more screentime in season 2.

Aside from flying through short stuff, like Entourage, I'd say it would be a close call between Alias Season 1, 24 Season 1, The O.C. Season 1, or Arrested Development Season 1.

I'm planning on getting Veronica Mars at some point, and from what I've read, I will go through those pretty quick too.

Babylon 5 season 3 & 4 I did in about 2 days each.

Doesn't really count since the seasons were so short, but I watched each season of Coupling in one sitting.

24 Season One in about a day and a half. The pathetic part is that it wasn't planned or anything, I just got hooked.

I did 'Friends' season 5 or 6 (not sure which) in one day...

other than that my friends and I used to have an all weekend party (friday to sunday) when a season of 'buffy,' 'angel,' or 'Dawson's Creek' came out... Where doing season 6 of DC next weekend because it was our first year of college and it will be the first time we'll all be together to do so...

I usually like to take my time watching tv sets. Most times I only allow myself to watch an episode a day because I want it to last a little bit and I want the cliffhangers to mean something...

I just did a "one-sitting" of Entourage: Season Two, on DVD. Not the longest of seasons, but still...

The girlfriend has HBO, so I wanted to get caught up quickly. That way, I could start watching Season Three at her place before it got too far into it.

Now, so long as she doesn't get wise to the fact that I'm only in the relationship for some Piven and Dillon loving, I'm set.

i watched the first 68 episodes of "scrubs" in 2 1/2 days. i was sick and i brought my laptop into my bedroom which doesnt have a tv. thanks to bittorrent i was entertained all weekend.

so im sure i have you all beat..sadly.

I watched Freaks and Geeks in two days. That's the only series I have actually bought. I get my other TV shows from Netflix, so it slows my watch time.

The OC. Never once saw an episode on TV. Had Game Rush credit bruning a whole in my pocket, figured, why not? Wrong. I had just broken up with my GF and had no job. I watched ALL 27 episodes straight. No sleep. Just Soda, Chips and some Smokes.

I once watched an entire season of Frasier (24 episodes) in one day.

Rob

I too got through season 2 of Entourage in about a day last week. I got through the first season of Lost in about 3 days last year. I also remember getting through each season of Buffy pretty quick.

Eh, not impressed. Me and my roommate watched both seasons and first two eps of season 3 on demand just last week. 12 (give or take) straight hours of Entourage.

I finished The Shield Season 1 in about a 24 hour span.

I watched all of the episodes of Firefly (14) in a day. After watching the first episode, I was hooked.

I did the first 2 seasons of Wings in a day

Lost S1 in about two days, next closest were Veronica Mars and 24 S1 in about a week a piece.

Unless you feel like counting Now and Then, Here and There, which I watched in one sitting.

Watched Season 1 of of battlestar galactica over a period of two days. My wife was so sick of seeing me sitting on the couch all weekend watching this show.

I blazed through the complete series of Farscape in a little over 2 weeks. One of those seasons I did in two days.

Uh, okay.

For me, it would be Veronica Mars Season 1 in 3 days. If it wasn't for school or work, probably one day.

BSG Season One probably holds the record for longest time to complete a DVD set for me. I watched the mini-series about probably when I got the set last Sept/Oct and have trudged thru 5 or 6 episodes, usually an episode at a time. Usually I'm a marathon watcher when it comes to TV on DVD. I think the pace of the show is just too slow for me, but everyone says how great it is so I keep waiting for it to hook me.

I watched the first season of Deadwood during an HBO free weekend.

I've watched quite a few shows in mini marathons:

Curb Your Enthusiasm. I didn't have HBO until season 4, so I quickly watched 1-3. It's so easy to just flip to the next ep, laugh, and do it again.

I did the same with Arrested Development's first two seasons. Because of Fox's stupidity I never knew what day or time season three was on, so I'll marathon that when the DVD is released.

Others
The Sopranos 1-5 (as above, lack of HBO.)
Six Feet Under 1-4 (as above, lack of HBO.)
24 (1 & 2)
Nip/Tuck (1 & 2) I'm waiting for S3 on DVD, I can't watch it on FX (not HD). CSI: Miami (1-3)
Oz (1-3 or 4): Netflix 8 out at a time when I was between jobs.
Tru Calling: I saw a few episodes during season one, that's all my work schedule allowed when it was on. I watched both seasons in about 3 days on vacation. I liked this show, it's too bad Fox killed it with time slots and new characters. I'll take Eliza over Jennifer Love anyday.

I actually like doing this. If I don't catch a new show but find out later in the season it's good, I'll just buy the DVD, catch up, and usually resell/trade it. With DVR, Tivo, and TV on DVD, alot of people no longer have show "appointments" (I've even considered dropping cable for a year). Even if I'm home when a show is on, I'll do something else because I can't stand commercials any more.

I think I did the Shield Season One in a 24 hour span. I know I've done one of the ST:TNG seasons in about 5 days before.

Lost: Season 1 - Probably 19-20 hours over a weekend. Half one day, half the next. Plan on doing the same with Season 2.