Funduc, makers of the excellent program Search & Replace, offers a freeware program called Search and Replace Regular Expression Wizard. It doesn't write the regexes for you, but it does provide a good deal of help. Here's the description (there are screenshots on the web page):
The Search and Replace Regular Expression Wizard is an application we made to help you create, understand, and debug Regular Expressions used by our Search and Replace windows grep utility. The wizard allows you to construct new expressions, or modify existing ones, using a term-by-term approach. You can visualize the effect of each term in a sample text you can paste into the program from the windows clipboard or retrieve from a file on disk. The effect of specific terms is presented in-context, using colors to distinguish the current term from other parts of the overall expression. 'Search' and 'Replace' Expressions are constructed/ examined in separate screens of the Wizard so you can work on each part semi-independent of the other. You can move back & forth between the Wizard screens to make adjustments or experiment. The sample text can also be changed at any point by returning to the starting screen. When you are satisfied, the final expressions can be inserted automatically in the respective fields in the Search and Replace main program dialog (if Search and Replace is running).
I don't think you need to have Search and Replace to use the Wizard. Anyway, since it's freeware, there's no harm in giving it a try.