I'm putting together a business plan and for financial planning it
would be extremely helpful if I could get my hands on some sort of
trend charts that I can use to predict sales. I know nothing about
this at all and the numbers I plug in are only guesses.

I'm told that banks have this type of information at their disposal in
order to validate financial forecasts when giving loans.

I am a software developer and will have three areas of business:
consulting, selling services and selling products.

I am looking for trends over a couple of years (preferably 5) for
small companies in each of these sectors (I assume they will be
different) and their performance so that I can model after them.
Ultimately, I would like the average trends but also, if possible, a
better case and a worse case trend for each.

I don't know if I communicated this requirement properly. Feel free to
question my question. ;)

Cornchip --

There are a number of ways to model sales trends.  The following
Google search strategy will help highlight it:
"sales forecasts" modeling

However, what the banks will be looking at will be whether or not
you've systematically analyzed the business or whether "the numbers
are only guesses."
*  how will product segments develop?
*  where will you add people to address new channels?
*  what are your per-person sales expectations?  how long does it take
to get new sales people up to quota?
*  what are ancillary product sales (upgrades, etc.)?
*  what does experience tell you about product life cycles?
*  what will new products/services produce?
*  what impact do you see from product cannibalization?
*  who are your top 2 competitors?
*  what do you know about your competitors' sales, margins, customers?

Finally, if you're looking for trends in this broad area, you might
consider Bizstats.com or another industry survey.  And don't rule out
the Economic Census of the U.S.

Best regards,

Omnivorous-GA

Thanks Omnivorous.

Your information helped. I think I'm done with this question and
should start heading in a different direction.

I just love this tool and jump to post questions before I think them through. ;)