this is my all-time favorite dynamics plugin, I use it on everything, and the EQ section is very useful. the body control can also result in some pleasing or interesting sounds, though i'm not exactly sure what it does or how it works. sadly, TBT audio has retired...but I am hosting this plugin here because I love it so much, and other people seem to like it too.
Blockfish from digitalfishphones is good on drums, in my opinion, and their dominion plugin does some cool stuff too. the simulanalog.org gsuite JCM-900 plugin is also great for direct guitar, and the univibe sounds good too. all of these plugins are free.
http://www.digitalfishphones.com
http://www.simulanalog.org
UPDATE: I'm really liking the kjaerhus audio classic series of plugins (master limiter and compressor are getting the most use, a good alternative to TLS maximizer ... www.kjaerhusaudio.com), and the project X reverb is easy to use and sounds great to these ears (www.pxe.buntweb.de). not a big fan of the x-amp however. and mda vst (www.mda-vst.com) has a big bundle of free VSTs, available in an easy to download big bundle zip file. I like the way "chimp" sounds on acoustic guitar for a song I wrote today (think my bloody valentine wall of fuzz). www.smartelectronix.com has a bunch of freebies available as well, from a large number of developers
for other free plugins, see the wonderful site www.kvraudio.com ... I reccomend sfz for playing sampled instruments with your midi keyboards...do a google search for "soundfont" and you will find many libraries of sounds to use (Fluid GM R3 is a good one to start with) (www.hammersound.net -- many soundfont libraries here). also, www.tweakbench.com has some very cool and fairly simple (easy to use) synths...such as a MELLOTRON! sampled one called tapeworm. and ZR3 is a good free organ synth. SIR reverb is free and you can find all sorts of impulses to use, you should be able to get a good reverb sound out of it. I also like Ambience. but I'm not really a reverb conisseur so keep that in mind. I just know these two sound better than the crappy ones that come with cubase. Amplitube sounds awesome for electric rhythm guitar, but it's expensive. if you can find "little green amp II" from wurr audio it's amazing for lead sounds, very versatile. comes with sonar 3 I think. I think it was a little too good...was discontinued probably for cutting into their greenmachine business. I will try that one someday when I have some cash (it's a lot cheaper than amplitube! only $80). I have gotten some good results from echomania, a quadruple tape-style delay. to find these plugins, either use google or the kvraudio.com dropdown menus. that covers my favorite VSTs for now
fin!