Fodder in DF can be a bit of an issue. Individually weak, they are often no threat at all to a group of DF delvers. They can get some critical hits, maybe, and do some damage, perhaps, but they aren't very dangerous or, really, much fun . . . unless you use them well.
I figure there are a few things you can do to make the individually weak fodder into a threat.
Have them bring friends. Lots, if possible.
"Dinomen don’t come in piddling numbers – they come in dozens, scores, or even dozens of scores." - Dungeon Fantasy Monsters 1, p. 11
Numbers are really only limited by physical space.
Since DF Fodder are nothing more than a distributed series of attacks with individual pools of HP, the way to make them tougher is put in more of them - and thus more attacks, and more HP.
Don't be afraid to use a lot of fodder. The "dozens of scores" line above might seem like a joke, but even 240 dinomen is merely a few minutes of action for a group of delvers, with Scouts knocking them off 2 per turn and front line fighters killing them as fast as they can swing. Part of the threat of fodder is that the 4-5 orcs you see now have the rest of their 3,872 buddies backing them up.
Bring a Special Friend
Bring someone tough enough to at least occupy the big bruisers on the superior side.
One of the Mikes, who runs Vryce, brought this up recently. In the Epic Lizard Man Fight, Vryce (and Raggi) were occupied with the really skilled guys. Had they not been there, any number of additional low-ranking lizardmen and newtmen wouldn't have mattered. He'd have been killing them as fast as he could swing. But those guys required his undivided attention, making the fight that much tougher (and letting the fodder accomplish a lot more.)
Equally, the presence of fodder allows the tougher guys to be a bigger threat, because the fodder give them the space and time to use their own skills without getting mobbed themselves. The fodder can mob the weaker delvers, or flank and disrupt the stronger ones, while the tough monsters get their licks in. The fodder also make riskier attack strategies difficulty - you can't all Committed Attack or All-Out Attack the BBEG if that means you take a bunch of clean hits from their lesser allies.
This really only works if the tougher folks treat the fodder as fodder; if they regard them as dependents to be protected they can't really use them as needed.
One subset of the special friend is the special weapon.
Use special attacks - siege engines, poison, fire, gas, and heavy weapons of all kind. These fill of the role of drawing off some fire from the rest of the fodder, but also provide a built-in threat to the delvers who can ignore the weak attacks of the fodder.
A prepared battlefield is covered here, too - pits, traps, barriers, etc. help to make the fodder just a bit tougher, or at least harder to reach. Ironically (but amusingly for the players) a theoretically well-prepared battlefield can serve to limit the ability of fodder to attack the PCs, if the PCs play their cards right.
Or at least, good tactics. I won't reiterate what I already posted here and here.
Remember, though, this can go too far. If the individually inferior foes are so dangerous, so nasty, and so hard to deal with that PC tactics center around avoiding them, you've moved them out of the fodder category. They're no longer inferior. They are no longer fodder, and players and the GM alike should realize they are worthy foes and probably center a bit more of the game's attention on them.