Well, it really depends what you want - mods can do virtually anything. Some of my favourites:
Gameplay enhancing
Tactics - In many respects it is cheesy, with monsters pre-buffing instantly for example. Wes Weimer points out that its no more than the PC would tend to do, which I tend to agree with. Whatever you feel about the ways in which this is done, there is no doubt in my mind that the game is made much more challenging by it, and it certainly does force you to be inventive. I wouldn't install that now though - start a new game. Oh, and stay away from Improved Illyich unless you're feeling truly hardcore... Check out Six's great review somewhere on these forums.
NPC flirt pack - really really good - gives you tons of party banter if you like that sort of thing.
Ease of use - most of this I don't install because its too cheesy for my liking, but it does have a few gems like 'bottomless bag of holding' that make the gaming experience a bit smoother.
Mod NPC's
Now the standard of some of these is simply amazing, you can expect much more interaction than with the default bioware NPC's, optional in-depth romances and their own quests etc - if you ever wanted to feel like you're in a real party of adventurers, these are the best you'll get in BG2.
My favourite - Keto, the permanently drunk bard. Some of her dialogues have made me laugh out loud, intereractions with many Bioware NPC's are most amusing, Keldorn trying to rouse her with a hangover for drill practice in the morning being particularly memorable.
Valen - Bodhi's assistant gets to be recruitable, complete with vampiric powers. Some say overpowered, she's been toned down in the most recent version - if ever you want to play an evil party, or see how a chaotic evil really behaves and impacts on your party, she's the character for you.
Next up, Kelsey. A sorceror who has particularly noteworthy dialogue when it comes to dealing with his awakening powers - struck me as being very well done. Worth putting in a party with Keto as they have a couple of really great banters together.
Soulaufein from Ust Nutha can join also. Many regard him as very overpowered, but at the same time inexperienced players find him very weak. If you're an experienced player who knows the ins and outs of the BG2 combat system then he'll be a monster at higher levels. Lots of quests, really really intelligent dialogue makes him another great option IMO.
This is getting a bit too long, so just do a search for "NPC mod review" for an excellent in-depth look at them. Tashia, Chloe I also enjoyed having in my party.
Additional storytelling
Ascension and Redemption both add a lot onto the end of ToB and give you lots of roleplaying options, harder ToB bosses, an option to redeem a certain ToB NPC. If you haven't seen the original ending of ToB yet though, hold off on these.
More misc
Item upgrade springs to mind, allowing you to do something useful with gems, demon hearts etc that you find in your travels (well, they do normally have descriptions involving magical usage on them!) - just be careful what you choose, because some items are overpowered.
That's your lot for now. As you can see, I favour NPC mods because I love the depth of party interaction that occurs. I wouldn't have more than two mod NPC's in a party at once though, because generally they don't banter with each other, only with the Bioware NPC's.
Valen, Sola, Tactics, Ease of Use can all be found at
www.weidu.org. You'll find most other things at
www.pocketplane.net or in the forum FAQ.
[ 03-18-2005, 06:19 PM: Message edited by: shamrock_uk ]