While not an expert, I'll throw in my suggestions. I love open source and free tools. I hate to pay for anything.
I use a lot of the instantposition tools you mentioned.
I also use the tools at
http://www.searchengineworld.com/misc/tools.htm
I have one on my site (which I think is pretty cool) at
http://www.divergentlines.com/resour...pment_tool.php it uses Google to find relevant link exchange partners.
I also use a tool called Good Keywords. It's a free program that shows several diffrent SE keyword searches (similar to Overtures KW suggestion tool). It queries Ov, OvUK, Lycos, Teoma, and others. You can get it
here
I never use the tools that query SE's with my domain. There is some evidence to suggest that the SE's are starting to clue-in to the fact that people are using these tools to avoid going to their sites (bypassing their advertising $) and are penalizing domains that are searched with these tools. Though I imagine this could be abused by competitors, too, so who knows... I just go with "better safe than sorry" in this case.
I'm curious to see what tools others are using, too.