I had a play with some simple scripting to pull data from area enclosed in brackets, I then removed obvious strings such as "Windows 98" or "MSIE 6.0."
There may still be some common ones remaining, but if I wasn't sure I left it in.
This is the list, ranked by count: (bottom 0.1% / <200 excluded)
9713 InfoPath.1
6045 FunWebProducts
5002 InfoPath.2
3946 IEMB3
2224 YPC 3.2.0
1375 Avant Browser
896 MSN 9.0
881 MSN 9.1
875 yplus 5.1.04b
851 MSNmen-us
803 FDM
751 Google Wireless Transcoder
654 NaviWoo1.1
644 TOB 6.05
632 DigExt
594 Maxthon
587 PeoplePal 3.0
545 Orange 7.4
522 MSNcOTH
509 Seekmo 10.0.341.0
448 SIMBAR Enabled
419 ZangoToolbar 4.8.3
402 WinuE v6
402 WOW64
382 Sky Broadband
370 Comcast Install 1.0
362 MEGAUPLOAD 2.0
359 J2ME/MIDP
356 Q312461
355 MSNbMSFT
349 MRA 4.10
345 ssr
342 tr
335 SpamBlockerUtility 4.8.4
330 MEGAUPLOAD 1.0
322 Arcor 5.006
299 YComp 5.0.0.0
289 MSNbMSNI
288 MyIE2
285 MSNbVZ02
284 Embedded Web Browser from:
http://bsalsa.com/
283 yplus 5.3.04b
282 Stream Plugin
277 T-Online IE7
261 SIMBAR=0
254 MSNbQ002
248 Neostrada TP 6.1
229 Zango 10.0.341.0
212 iebar
212 DT
211 America Online Browser 1.1
210 Comcast
207 MSNc00
207 AtHome033
203 SeekmoToolbar 4.8.4
202 RRHSO_BLD1
202 MSDigitalLocker