How much resistance is needed in inferno for a melee class?

I got some lightning resist, and with the Monk's One With Everything passive, that puts all my resists at 200%, but I still think that is too low.

How much resistance does a melee class need to be effective in Inferno?

There have been various debates over the effectiveness of stacking resist. I'd say that it's extremely helpful, but make sure you maintain a decent amount of health and damage. Focus on one resist and take the passive if you want to build this way. Around act II or III, you can reach at least 300 resist (at least 50% resist).

While there may be several viable stat builds, resist is definitely one of the most effective. Why? At the higher difficulties, the only true threats are elite packs and champions that use Arcane Enchant, Molten, Fire Chain, as well as several other damaging skills. Resist helps to counter the majority of these.

Playing lvl 60 barb with around 700 all resist, meaning (according to the ingame inventory tooltip) 68~71% damage reducing, 9k def, 47k hp, 8,9k dps 231% crit amp. and doing inferno act I easily as hell. Tanking (mean standing in arcane / plague / fire spells damage area 50% of the time) any elite pack without any problem, taking just the "bomb time" (Berserk + Inferno) to kill those. Already soloe'd butcher in around 3min without poting. The thing IS, when it comes to act II, my friend, the whole scene changes. The damage is much higher and reading some forums, the resistance starts to make some effect at around 900all.

I have almost no resistance, and on my monk, I do ok soloing in Inferno, and I estimate I can kill about a third of elites without dying, half with maybe 1-6 deaths, and I abandon about a sixth of the packs.

Run speed, dodge (which is also damage), and crowd control skills alone are enough to do extremely well.

I use all of my crowd control skills, Mantra of Evason with run speed, run speed boots, run speed passive, and Deadly Reach as my only damage dealer.

None is needed.

Note that this answer is about monks - I don't have a lvl 60 barb.

All you need for a Monk really is 600-700 resist all. My monk is lvl 60 with 620 all resist. Don't base yourself on LOH dps and be a tank (boring and slow) - I have 2.20 speed with 33kdps with Deadly Reach. I am at 50K+ dps with armor at 9k and 47k+ HP.

I clear Act 3-4 pretty fast =). To tell you the truth I feel no difference between Act 1 and 3/4.

Speed for monk is still the keys for soloing. =)