I have a calculated field that concates several fields into one. I want some of the text to be bold. Is there some tag or something I can put in the formula to specify bold text?

Heh... nope. Just isn't. I hate it, but their isn't. The best scenario I can give you is the rather obtuse one of running an applescript and using the Do Menu step, and just having it press the bold button for you.

Or buy a plugin, there are several out there

There is a trick to accomplish calculated field formats. With this trick you can set any text or part of it to any format:

Firstly, lets say we have three fields: Name1, Name2, Dateofbirth

Example:

John

Brown

11.11.1968

OK!

Now simply paste these fields as Merge Fields onto your layout Because these are really only place-holders entered as text, you can format each merge field to what you want.

If you want to be able to search this result, then simply create a calculating field that gives us: John Brown 11.11.1968. Now make sure your Text(merge Fields) are brought to the front and use the same fill color as the background, now hide the calc field behind this text.

Hope this helps - Rigsby