Several companies rely primarily on customers downloading a software product (or white paper), evaluating it, and then making a purchase decision.
Collecting an email address at the time of registration allows customers to recieve monthly newsletters, but what's really needed are precise, automated email follow-ups at specific milestones within the evaluation process.
The following image shows a basic 30 day evaluation process and some potential key milestones.

Notice that the customer does not have to wait until the next monthly or quarterly email newsletter to be exposed to your marketing message.
Product evaluation campaigns can be as simple or as sophisticated as needed. 3 general types of lifecyle campaigns include:
1) Immediate auto responder with timed follow-ups.
In this scenario, a prospect visits your site and completes a download request form (to reduce abandonment rates this should be kept to a minimum, such as email, first name, and last name).
They immediately receive download instructions via email and are free to install and evaluate the product.
Then, at defined intervals, the prospect automatically recieves follow-up emails with more information about the product and "call to action" link to purchase the product (note that these emails do not assume much of dialogue context, such as have already spoken with someone on a phone).
2) "Smart" Email Follow-Ups.
This type of campaign is the same as the above mentioned campaign, except that each email makes a "smart" determination as to what the customer needs based on what is known about the customer.
Examples include a role-based call to action (Economic vs. Technical justification for product) or a custom follow-up to an online KB article search.
3) Product Integration.
The holy grail of product evaluation automation is having the product actually tell i-Dialogue when certain evaluation miletones have been achieved and sending emails in response to these milestones. Emails can be sent to the prospect or inside/outside sales reps.
For example, if 20% of all prospects don't even install the product, the nature of the email messages should continually remind them that online installation and configuration support is available. Conversely, if a prospect *has* installed the product, then the tone of follow-up emails should provide some information that leads towards a purchasing decision.
Evaluation campaigns do not neccessarilly need to be driving towards a purchase milestone. They can be in response to white paper downloads that are cultivating a lead for a phone follow-up, test driving a car, or visiting a casino.
There are myriad options and opportunities here. The key is that these mini-campaigns are not synchronously tied to your larger campaigns. They are initiated and matured based on asynchronous factors and milestones.