If you like this game, like i do, have played through it 5 times to date.
Then you should look out for a copy of Armed and Dangerous.
Although not quite as good overall as Giants, the humour is there, and some of the weapons are hilarious.

Is that the same one that had that "gravity reversal" weapon that flipped the whole game world upside-down and made all the enemies fall... up?

That would be the Topsy-Turvy bomb. Almost as badass as the World's Smallest Black Hole.

I have Armed & Dangerous, if you don't, nag a copy somewhere. It's an awesome game and all the style and the humor that you see in giants or MDK, it's there too.
You can see MDK, Giants and A&D as steps of an evolution, in MDK you go around zapping everyone, in Giants you do the exact same thing (in the first part of the game at least) but with the addition of the Pub to buy weapons/recharge, the team systemm destructable environment and other little things. A&D takes all the innovations of Giants (you will find the pub, and all i said before) with all the perfections it needed, like the lousy aim (in Giants it's really hard to aim someone, you gotta be really precise), the teammates IA and stuff like that. Besides, in A&D the weapons are really wacky like the Land Shark, the trumpet/mortar and the bombs you already mentioned.
Bottom line: liked giants? Go get A&D, it's a must.

Your mother was a... basketweaver! Noooo!
I gotta go find that game again :) thanks for reminding me!

I concur with Armed and Dangerous. Funny game. Check it out if you haven't already.

keeping those smarties from falling is proving too difficult for me

If you've already played through Giants, then the humor in Armed and Dangerous will seem less creative. It's like a second pass really, and it ends really abruptly.

It's unfortunate that more games don't employ this kind of humor.
A&D is definately a game to get if you want more of this type of game. You will thank yourself in the end for trusting the advice of everyone here.
Trust us :)

That's what I can remember from reviews of it at the time. "Like Giants, only more, but really REALLY short" :-/

Hah, I should've guessed they also did Armed and Dangerous, so obvious now. Such an amazing game.

For people wanting to get A&D, since it's not available at GOG, you can get it at
http://www.consumerdepot.com/products.asp?id=023272403188&referer=srch
for $0.99 + shipping (which was only $4 for me)

It was published by Lucasarts. So its appearance on GOG would be a great thing indeed. The actual gameplay is pretty conventional. Although the weapons definitely are something special. It's the cutscenes that make that game. Probably the best cutscenes of any game to date. Probably.

A&D is one of my favorites. If you are in doubt about getting it, watch this clip...
http://www.youtube.com/watch?v=XmPqnKvbiiQ