I've read and taken in swombats post to 'stop offering your services', and I think that he may have a point in the general sense, that some may abuse this format to gain a business advantage.
That said, I think it is much too early to make the call to stop doing this, let's fix problems if and when they appear.
The way to deal with that is to take any Offer HN at face value unless there is proof that it is not what it seems to be, and to indcate that if and when it appears.
From what I've seen so far all - or at the very least most - of the offers that have been made are both genuine and heartfelt, and at some personal expense in terms of time, effort or even goods to the person offering.
So please do keep them coming those 'Offer HN' postings and let's hope they will put HN on the map as a place where people do more than just talk.
I wouldn't want to see the Offer HN thing become a lasting trend at the current levels... that said, the odd "Offer HN" doesn't bother me, and I certainly wouldn't want to think that all offers stopped completely just because my post got upvoted.
That said, to elaborate on the point jacquesm singled out, many/most services-businesses (from tax consultancies to seo consultants and web developers) use free consultations as a way to generate leads. My suggestion to people who want to offer something to HN is, don't do it just to generate leads, and try to make it clear to the readers that it's not something you're doing to generate business for yourself. It'd be a shame to see some percentage of this site become basically a lead-generation site for the brazen few willing to take advantage of it like that.
PS: I'm not suggesting that any specific "offer HN" post was like that, despite mentioning examples above.