yeah... PS:T was impressive.
I wonder how it compares to Oblivion/Morrowind with its hundreds of books.

I'd recommend Ultima VII.
There's not a huge amount of fighting, and it's not difficult anyway.
Also, lots of dialogue and a great story.

Most of the Interplay/Black Isle DnD games excluding the Icewind Dale ones (BG1,BG2, PS:T) , especially as has been mentioned already - Planescape. The Bioware games Jade Empire and Mass Effect are mostly dialogue, too even if there's some fighting.
Most of the Troika games (FO,FO2, Arcanum, Vampire the Masquerade Bloodlines) are like that too - you can basically play through the game without combat if you'd like. You can also get through ES3:Morrowind barely fighting at all if you play a thief class or a member of House Hlaalu. ES4:Oblivion, not so much.
Incidentally, if you own a console the Xenosaga Games are about 80% story and 20% gameplay. You might like them. No branching paths though.
Have you ever played visual novel games? You might like them, too. Technically not RPGs, but extremely dialogue heavy, with branching paths. A commonplace example of this would be something like Phoenix Wright. They're very popular for the DS right now. Personally, I really like them.

Mass Effect. Way too much damn talking for my taste.

That's interesting... I never knew that there were any games out there that you could talk your way through fighting.

Really? I didn't see it as being particularly dialogue-heavy as RPGs go, even taking into account all the optional dialogue you can have with your crew on the Normandy. I guess the shooty sections were usually fairly brief, though.

my point made. =)

Talkie RPGs are down since too many kids with attention deficite disorder entered the primary buyer market. Mass Effect was supposed to be a fresh gust of wind in this department but doesn't really deliver due to too much filler around a forgettable main story.

Couple of things that is not completely correct...
The Baldur's Gate series (and the Infinity Engine it self) was developed by Bioware, and Fallout 1 & 2 was developed by Black Isle.

Well, I spent less time talking to people than I did doing everything else, and the plot worlds in particular had much longer action sequences than the brief sidequests - and the sidequests were even shorter on dialogue than they were on action. Probably half of the dialogue I saw was completely optional, being unrelated to any main or sidequests, and on top of that I constantly wished that my companions had more to say than they did. If it was dialogue-heavy, I sure didn't notice.

Planescape Torment is the main example of that. The final boss of the game can be defeat within the final dialogue sequence (which is quite lengthy by itself).

Planescape Torment. One of the best games of all time simply because of how rich the dialogue is along with many (I put an emphasis on many) choices that can make a bleak situation have unexpected results for good or bad.
Best part? Like the Fallout games you can avoid killing the final boss and talk him out of a fight.

Technically, you're right. Well, half right. The infinity engine games were all published by Interplay/Black Isle. I never said they were all developed by them.
Troika did not exist when FO1 & 2 were dev'd (their first game was Arcanum), but the BI members involved in FO mostly went on to form the core of the Troika team. BI isn't really one dev, either. It was the name for interplay's in-house dev teams. Colloquially, I refer to the FO team's games as Troika's games. We'll split the difference? LOL. Perhaps I should've been a bit clearer on my use of retronym.
You are right - Bioware was the dev for BG1&2 (with BI/Interplay as the co-dev/co-pub). Bioware never really got marquee billing as a dev until after KoTOR (even though they did come through with lots of great games prior), so the name doesn't really jump off the box cover until after that. With JE and ME it's in big bold letters. I tend to think of their earlier games in terms of the publisher, Interplay, but that's just me.
Some clarification: FO1&2 are BI/Interplay, but the Troika dev team is mostly the BI members who worked on FO1&2. Most of the BI/Planescape team members wound up at Obsidian. It gets incestuous after that. Obsidian keeps picking up sequels from Bioware (KoTOR2, NWN2).
Back on topic:
OP, you ever play PC adventure games? Like Dreamfall? The Longest Journey? That kind of thing? You may like them, a lot. Lots of dialogue choices, virtually no combat. I know a lot of people are soured on the genre, but there are a lot of really good games in it.

TLJ is a definite gem, Dreamfall as well, at least so far as I've come (I got stuck somewhere and then never bothered to try again, maybe soon).

Actually, I should have recalled some of that. Thanks.