I am using webconfs for back link checking and reciprocal link checking.
For backlinks purposes i use Yahoo site-explorer through Seo-Quake. Just a click away. I don't bother monitoring my competition's backlinks, but i do see them once in a while if there are any relevant pages where i can possibly place my link too.
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you can use automated tool to check back links of a website i.e. back link checker tool, yahoo site explorer, Google webmaster tool. But these tools cannot give you accurate result, so check back link of site manually by using:
link: site url It shows the all the back link of site in a better and accurate way.
I usually use Y! Site Explorer but sometimes I also use BacklinkWatch but I don't find it impressive.
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I only use Yahoo Site Explorer for checking the number of backlinks...I think that is enough..after all we rarely know which backlinks are weighty and which are not. I prefer doing more and more backlink building instead of going on checking backlinks cos I think it is of no use