Some slightly helpful tips
We haven't unlocked the secret to the same problem entirely, but we're getting there. Our little guy ate almost everything when we first started him on solids (except lentils - never liked them

). Once he started day care, he got sick frequently from the exposure to other germs, and because he was underweight, we simply fed him whatever he wanted. He soon caught on and started refusing the stuff he used to like: if it's colourful, he won't touch it. If it's bland in colour, like bread, meat (usually, not always), potatoes and fish, he'll usually eat it.
I try and put three things on his plate at each meal (except breakfast - he'll take almost anything at breakfast because it's carbs and eggs): something he generally loves, something he often eats, and something he probably won't touch. We've started insisting that he stay at the table until my husband and I are done (we only take about 20 minutes or so to eat on any given night - this rule would not apply if we had adult company over). So long as he isn't overtired from an active day, he often at least touches the food he doesn't like, and he may put it in his mouth. Even if he spits it out, we consider it a success that he at least tried it. We often won't replenish the stuff he loves until he at least tries what he doesn't like. But this we play by ear: if he's tired or overly cranky, we don't attempt it.
He goes to day care, so we often try and pack him a lunch that looks like what they're eating. We've had mixed successes with this: he has eaten green beans, and I did up a mexican taco mix (drug-free beef and spices) with food-processor finally chopped carrots and green peppers. Add unsalted nacho chips, and he ate it all. And this was inspired but what they were serving at day care. But he'll sometimes eat his vegetable soup, and sometimes he won't, for example.
My sister did the more traditional make-your-kid-sit-at-the-table-until-they've-eaten-everything, and she said that while it was stressful for a few weeks, my nephew (one month older) does actually eat everything. But it's not quite my chosen way of doing it yet (or my husband's).
So we're still looking for ideas ourselves, but we've made some headway with the above, slightly more gentler approaches.
I'll certainly be watching this thread for any more tips!
Trooper, Mom of Khristopher, 21 months old