Hey Memo, that's a pretty interesting question. The answer is pretty much what you won't want to hear...it's up to you. I mean, for most applications you could probably have an order, but it all really depends on what you're looking to do. Think of it this way...
With effects, it's helpful to think of it logically and how it will affect the source's outcome.
Depending on where the effect is in the chain will decide which effect is emphasized. The last effect will almost always be the dominate effect. If you have a verb followed by a flange, you'll have a swooshy, watery sounding reverb. If you reverse it, you'll be adding a tail onto a flanged source.
It really all depends on what you're trying to accomplish. I usually have an idea what my final sonic goal is for a song, then I try to logically figure out how to achieve an end result. Here's a real life example of what I mean...
In my tune "On My Side" (http://www.mp3.com/alphadog) I wanted the background vocals to be a tight solid group but still maintain a little seperation. I wanted them a little thinner than the lead, but still be full. Here's what I did...
First, I edited out all of the breaths and silent sections. This would be like adding a gate, but it's easier for me to just do it by hand, and it saves CPU resources. Then, I slightly compressed each of them seperately to even out the individual performances and make them more uniform (note: I thought about doing this while I recorded the part in the first place, but didn't for some reason), then I took out some bottom end in each (I wanted something a little more crisp). I then sent them all to sub mix (each panned to their respective spots in the mix) where I really compressed the hell out of them with a stereo compressor (I wanted their dynamics to be totally squished). I then added some slight chorus to fill in the gaps (because I still wanted a full sound, not individual voices so much). I added some reverb. The EQing I did to each of the parts before ensured that I was EQing the vocals, not the effects.
I knew what I was looking to accomplish, and I had to sit there and plan out the best way (that I could think of) to accomplish my end goal. Other songs didn't require such a plan, because my goal was different. The goal required that the effects be inserted in a specific place. Someone else may have done it differently, but this was my plan.
I know this was pretty long winded, and I probably didn't answer the question (ha!), but I hope it helps a little.