automatic text replace needed

Hey there,
for two weeks now i’m digging throught the plugins offered at wordpress trying to collect the good ones, but there is one tool, the main tool, missing. I only found some that were similar or not uptodate. Honestly i feel like i already know ALL plugins there are(and dl’ed half of ’em)! ??

Since i only have a few hours a day for the blog my time is limited to writing posts only and researching, so i need a tool that automatically replaces certains words with links from the blogroll(or whatever). I want to do this in the adminarea when i write the text, not some automatic plugin/process that slows down loading times.

So far i only found one tool that allows me to replace text, but i need a tool atuomatically searches the text for words that are connected to a link.

example:
“On my way to the mall i met John Donson”
Now in my blogroll(or whereever(whatever the plugins needs for this)) i have links that connect the words “mall” to “www.mall.com” and “John Donson” to “www.johndonson.com”

Time-saving is the most important thing in this case!

I only want to enter links once and then use them automatically over and over again in every post over the blog.

It would be also very helpfull if anyone knows a tool that works similar and connects words internally to other posts with the same topic compatible with the actual version of wordpress.

I found some stuff on coffe2press, but those version were made for early wordpress version and i don’t know if they still work, i don’t want to mess up my blog!

Please help!

Akribik