Some very use full applications of mac must need
Adium: best im client ever build is for mac it is better than pidgin.
it support multiple im’s. Also there are lot of ready made scripts for multiple jobs (mostly for quotes from movie or celebrity).
Adobe acrobat reader: you have preview but still you will need it some time because preview has it’s own limitation . It make the portable document format not so portable. So when you open a document which is made from windows using words/power point you will not able to see exactly same as it is with preview.
Some fonts figures will not be displayed. It has really got on my nerves then i found that preview is best but i don’t know why they have done this to preview. Why a portable claimed document is not portable why i need adobe reader while i have best reader preview which is so light weight so fast so easy to handle.
Gimp or adobe photoshop:even if you are not photo fan you will need it sometime.
Alarm clock.
app cleaner: i don’t know why mac has so bad way of deleting files . when you delete some application many of its preferences saved profile still remains in multiple location like library etc. You have to search and remove them manually. it is good if you are removing something temporary and you will need it after some time then you wish that your history will remain but this kind of delete is very rare generally we want complete remove of program from computer so mac will not be able to do this so u will need some application App cleaner is best.

Aquaemacs: for emacs guys and for oz compilation.
BBedit best editor. as helper to textedit.
better in some ways than textedit. support many text file formats.

Colloqy: irc client
cover sutra:
desktop lyrics:

No good video player in mac. vlc also not provide all it’s functionality as in windows(e.g. Subtitle synchronizing). This is worst thing. i miss Kmplayer i really don’t have one good player in mac.

vlc media player:
djoplayer:not required
djvu: djvu file reader for listening un compressed .flac format music files

Gimmesometune: Automatically fetches lyrics and artwork for itunes.

ilovestar: If you wish to rate songs and see there rating from apple menu bar
ichm: .chm reader.
iscobller: scrobbler. Scrobbler from is unstable in mac. iscrobbler provides more facility like local user charts and history.
justlookin: light weight image viewer.
iwork/microsoft office
name mangler:
opera: best browser. i got frustrated from safari . it is light weight loads fasts but still some pages some redirects don’t work you really can’t bear this.
shakespear: OK DC++ substitute
Xtorrent: Best torrent client. Provide search and feed inside the client.
transmission: Good torrent client
Adobe Lightroom:
FileZilla: Best Ftp client for mac. easy and friendly to use, light weight.
Name Mangler:
Unison: For newsgroup