ok, here are the must have apss in my opinion and probs some agree, here they are:
*Advance Task killer - lets you kill unwanted tasks, good for freeing up memory, but kills selected tasks and add some to ignore that are required, more info is on forums, and yes you do need it regardless of what people say, every smartphone should have one. its how you use it that matters.
* Astro file manager - this is probably the best file manager around for android, it lets you go into your drives and edit,delete,add, move etc folders and files, so you are in control of it.
* Mp3 Download - the title kind of gives it away, if you love music this is for you, lets you search for a song, click it and download it for FREE
easy as that. (bit like limewire on pc but its safe and its on your phone.)
*My Backup/My Backup pro - this is vital i think, everyone should do backups, and this app does exactly what it says on the tin and backs up your data,messages,settings and apps. either to your memory card or a online server. take it from me tested and it worked, backed up on one desire and restored on my new desire.
* ebuddy - if you like chatting away either on fb or msn and love the messenger on both then this app is for you. Lets you add both your msn or facebook and probs more to it, and you can chat on both and at same time if you want, great interface and brill app.
* gearoid (sega mastersystem)/ super gnes - If you are a gamer and love playing games,then this is for you, go oldskool and download these emulators these are brill, jsut downlaod the roms off net onto your phone and play
* world cup 2010 fotmob - football person? this app deffo for you, especialy with the world cup coming up, keep upto date and have the altest score and info on your phone on the move. brill app.
* video box - lets you download youtube content straight to your phone.
xialive - lets you stream online radio, really good, sectioned into diff genres, great app, also can conflict with mp3 download in a good way allowing you to preview the track before you downlaod.
* barcode scanner - lets you scan barcodes giving you prices, also can scan barcodes to get apps for your phone as the image is a link to a site/app.
* OI notepad/OIsafe - lets you keep your passwords safe and secure and the notepad lets you save important info.
these are some of the best and must have apps in my opinion, there are probs more, but these should keep you pre occupied and help others aswel here
enjoy