Well, I have to agree that we've gotten too paranoid here, and think we're capable of having a general discussion about a legal issue without giving legal advice.
And I also agree that not everybody here can afford to run off to a lawyer every time a legal issue comes up. Not all of us here have the luxury of being able to consult ourself. ;) So, I'm going to push ever so gently on the edge of the envelope.
I think you have to start by reading about the trademark laws in your country, starting with the official website of your trademark office. In most cases, I think you will find not only the law itself, but more readable summaries and guides. In the U.S. there are some quite-specific guides - even dealing with domain issues.
Realize, too, that international and foreign laws may apply, but your trademark office is a good starting-point.
When you do that, I think you will find (at least for the U.S.) that trademarks are not so broad as to preclude the use by anybody else, but only by anybody else within the specific industries declared by the filer.
In other words, IBM does not claim a trademark on all uses of "IBM", but in certain industries - say, computers. (Caution: look up the trademark, and see what industries they have filed on. There are often several, and some might be surprising - sidelines, abandoned product lines, etc.
There's a simple moral test that, while it won't substitute for the precise legal test that only your attorney can advise you on, I think will work most of the time: are you trying to take advantage of and draw traffic because of somebody else's famous name?
We had a good local case a few years ago. A resale shop operated for several years with the creative name "Sacks Fifth Avenue". It took a few years, but I think you can guess the inevitable result: Saks Fifth Avenue sued.
Sacks Fifth Avenue claimed that there was no way anybody could confused them with the real Saks Fifth Avenue, as they were a resale shop, and Saks sells top-of-the-line new merchandise. Saks made the point that they'd recently opened an outlet store in the area.
The judge sided with Saks, and Sacks was sacked.
Oh, the store *was* on Fifth Avenue. Now, what if they'd actually been selling sacks?
While I can't guess the outcome, I can imagine that it would have been an even BETTER news filler than it was!
Every website owner really needs to understand the basics of trademark and copyright. And here's where that expensive lawyer comes in. I think it would not be a bad idea, AFTER reading-up, to schedule a half-hour or hour with your attorney just to ask "do I understand this right?". Then you can ask your specific personal questions and "what ifs" that you can't ask here. This might be more important, actually, than seeking out an attorney when a situation actually comes up. If you understand the law, a problem is less likely to come up later.
Now, be good little boys and girls, keep "me" and "my site" out of the discussion, and maybe Santa won't leave you a lump of coal.